While the Bible tells us we have to be Born Again of the Spirit, it tells us nothing of the mechanics involved. What exactly is it that, in so many cases, causes people to have such astounding conversions and becomes so totally different? While it is true that many others have 'quieter' conversions, if no change at all occurs in a person's life, the Scriptures say that there is a very good chance true conversion never took place to begin with. Being Born Again of God is commonly believed to be in a figurative rather than a literal sense. But what if it is not? What if this being Born Again of God, or being fathered by God, involves very literal physical changes, which leads to a total transformation of the person? If, as shown in the linked article, it is very likely that Adam and Eve's epigenome underwent some drastic changes, why wouldn't true Biblical repentance and a conscious decision to follow Christ result in God re-setting' the altered Epigenome which, in essence, would be a new birth from above. See Original Sin or Epigenetics
The Bible uses two terms (converted and born again) to indicate a change that is required before a person can be counted as one of God's family and admitted into His kingdom. And there is a good reason for this. Human nature has to be changed to make it fit for the kingdom. Without that transformation there will never be serenity, security, or harmony in Godís coming kingdom, this amply proved by man's history. See The Warning of The Bible
Note that as retired Anglican clergyman Dick Tripp points out
... the idea that we are sinners, separated from God, and needing reconciliation to him is in marked contradiction to the Hindu, Buddhist and New Age ideas that we are all part of "God" and that all we need is to become more fully aware of that. The Bible diagnoses our position as being somewhat worse than that and beyond our own capabilities of doing anything about. However, this offer of spiritual life is available to all who want to be part of God's family through what Jesus has done on our behalf.  See Overview of The New Age
Conversion in the New Testament
Using the Greek verb strepho (to turn, turn around) Jesus made the following statement in Matthew 18:3,
And He called a child to Himself and set him before them, and said, "Truly I say to you, unless you are converted (Gk. strepho) and become like children, you will not enter the kingdom of heaven. (Matthew 18:2-3 NASB)
The dictionary meaning of 'convert' is a change to another attitude or belief - a word we commonly associate with the adoption of a different religion. However, it is very possible for a 'converted' person to do no more than observe the required physical rituals of the new religion. In other words, one can attend a church service, pray in a mosque etc. without any changes to one's lifestyle, patterns of behavior, way of thinking etc.
However, Jesus' meaning was far deeper. In the New Testament a form of strepho - the Greek verb He used is often seen in the sense of turning from sin to God...
Therefore repent and return (Gk. epistrepho) , so that your sins may be wiped away, in order that times of refreshing may come from the presence of the Lord; (Acts 3:19 NASB)
And all who lived at Lydda and Sharon saw him, and they turned (Gk. epistrepho) to the Lord. (Acts 9:35 NASB)
to open their eyes so that they may turn (Gk. epistrepho) from darkness to light and from the dominion of Satan to God, that they may receive forgiveness of sins and an inheritance among those who have been sanctified by faith in Me.' (Acts 26:18 NASB)
but kept declaring both to those of Damascus first, and also at Jerusalem and then throughout all the region of Judea, and even to the Gentiles, that they should repent and turn (Gk. epistrepho) to God, performing deeds appropriate to repentance. (Acts 26:20 NASB)
For they themselves report about us what kind of a reception we had with you, and how you turned (Gk. epistrepho) to God from idols to serve a living and true God, (1 Thessalonians 1:9 NASB)
The critical importance of this turning is perhaps best understood in light of James' words. Most people do not deliberately set out to abandon the truth but just sort of wander away from it. James reminded his readers that anyone who turns the wanderer or sinner from the error of his ways and re-establishes him in the truth, has saved their life
My brethren, if any among you strays from the truth and one turns (Gk. epistrepho) him back, let him know that he who turns (Gk. epistrepho) a sinner from the error of his way will save his soul from death and will cover a multitude of sins. (James 5:19-20 NASB)
Being "Born Again" In The New Testament
The Gospel of John tells of a conversation Jesus had with Nicodemus who as a member of the Sanhedrin (the supreme council and tribunal of the Jews) was a man of high standing in Jewish society, thus quite likely to have been wary of being openly seen with Jesus. Almost the first thing the Savior said to him was that unless a person was 'born again' he would not see the kingdom of God (John 3:3).
Now there was a man of the Pharisees, named Nicodemus, a ruler of the Jews; this man came to Jesus by night and said to Him, "Rabbi, we know that You have come from God as a teacher; for no one can do these signs that You do unless God is with him." Jesus answered and said to him, "Truly, truly, I say to you, unless one is born again he cannot see the kingdom of God." (John 3:1-3 NASB)
Note carefully that Jesus didn't suggest a new birth. He didn't tell Nicodemus that his life would be drastically improved if he was reborn. He unambiguously stated that unless a person was 'born again' he would not see the kingdom of God.
Other New Testament verses also speak about the 'new birth'
But as many as received Him, to them He gave the right to become children of God, even to those who believe in His name, who were born, not of blood nor of the will of the flesh nor of the will of man, but of God. (John 1:12-13 NASB)
Blessed be the God and Father of our Lord Jesus Christ, who according to His great mercy has caused us to be born again to a living hope through the resurrection of Jesus Christ from the dead, (1 Peter 1:3 NASB)
for you have been born again not of seed which is perishable but imperishable, that is, through the living and enduring word of God. (1 Peter 1:23 NASB)
However, I can imagine that the term "born again" can be very confusing to many people in more ways than one. Many might simply wonder how in the world someone can be born a second time. Others associate the phrase with a new lease on life. The phrase is often associated with an ardent, earnest, and devoted form of Christianity conjuring up, as Presbyterian pastor and author Timothy Keller said in a recent speech, visions of a specific "type of person" ... "emotional" people who worship with raised hands and crying Ē 
However, as you can deduce from the following examples, this is not how the Bible uses the term. In the New Testament being "born again" refers to something God does when we turn to him with repentance and faith. John, who told us the story of Nicodemus (above), used the expression more often than any of the other New Testament authors.
1. If you know that He is righteous, you know that everyone also who practices righteousness is born of Him. (1 John 2:29 NASB)
2. Whoever believes that Jesus is the Christ is born of God, and whoever loves the Father loves the child born of Him. (1 John 5:1 NASB)
3. For whatever is born of God overcomes the world; and this is the victory that has overcome the world - our faith (1 John 5:4 NASB).
4. No one who is born of God practices sin, because His seed abides in him; and he cannot sin, because he is born of God. (1 John 3:9 NASB)
5. We know that no one who is born of God sins; but He who was born of God keeps him, and the evil one does not touch him. (1 John 5:18 NASB)
Please note: In examples 4 and 5 John was not telling his readers that they would never ever sin. The Greek grammar in both verses makes it clear that John is speaking of someone who makes a practice of sinning - a habitual sinner.
What Happens When We Are "Born Again"?
It is generally believed that two things happen.
The First is that God forgives our wrongdoings.
The word justify (Gk. dikaioo) means to 'show to be free from blame or guilt'. Dikaioo is linguistically related to dikaios (righteous) which Jesus used in Matthew 25:46 to tell us that the righteous (dikaios) would go into eternal life.
In Luke 16:14-15 the Pharisees tried to justify or make themselves look innocent in the eyes of their fellow men. However, as Luke said God knew their hearts - their qualities that their contemporaries highly esteemed were "detestable in the sight of God".
However, it is another matter altogether when God Himself justifies us.
In the book of Romans Paul frequently used the term justify (Gk. dikaioo) to tell us that we have been exonerated or acquitted of all charges against us and declared innocent. In other words, because Jesus paid the price of for our sins by dying on the cross we have been acquitted of all wrong doing and made right with God. See Salvation
However, that our sins have been forgiven and we have been declared righteous is simply not enough. We need more if we are to live as God intends for us to live and avoid all the pitfalls that will undoubtably present themselves.
The Second is that God's Spirit (the Holy Spirit) in a manner of speaking, comes to live in us. As Peter told the crowd on Pentecost
Repent, and each of you be baptized in the name of Jesus Christ for the forgiveness of your sins; and you will receive the gift of the Holy Spirit. (Acts 2:38 NASB)
Please note that Peter was not telling his audience that they would receive the gifts of the Holy Spirit i.e. healing, miracles, etc. but the Holy Spirit itself. That this would happen was foretold many centuries earlier by the prophet Ezekiel,
"Moreover, I will give you a new heart and put a new spirit within you; and I will remove the heart of stone from your flesh and give you a heart of flesh. "I will put My Spirit within you and cause you to walk in My statutes, and you will be careful to observe My ordinances. (Ezekiel 36:26-27 NASB)
Before we receive the Holy Spirit there is a great chasm between us and God. As Isaiah said 'our iniquities have made a separation between us and our God, And our sins have hidden His face from us so that He does not hear.' Paul said we were dead in our trespasses and sins, sons of disobedience, walking according to this world and according to the prince of the power of the air. (Ephesians 2:1-2)
So what does receiving the Holy Spirit mean? Steven J. Cole of Bible.org explains it simply but effectively.
Just as the person filled with wine is under the influence or control of the wine, so the person filled with the Spirit is under the Spirit's control. Furthermore, Paul is talking here primarily about a condition of increasing spiritual maturity, not about a momentary experience... The present tense of the verb indicates an ongoing condition, so that the person may be characterized as "full of the Holy Spirit." 
As the Bible says,
Therefore if anyone is in Christ, he is a new creature; the old things passed away; behold, new things have come. (2 Corinthians 5:17 NASB).
In other words, it is not just a temporary emotional or mystical high but a new beginning.
Also See What is The Holy Spirit? - A Separate Person or The Divine Presence And Power Of The Father Himself
Part VI of Is God a Trinity
Is There a Third Something That Happens?
Being Born Again of God is commonly believed to be in a figurative rather than a literal sense. But what if it is not?
What if this being Born Again of God or being adopted into God's family involves very literal physical changes that leads to a total transformation of the person?
The recently emerging field of epigenetics may actually give us a clue as to what Paul was actually referring to in Romans 5 in which the apostle seems to be saying that something happened to all humanity because of what took place in the garden of Eden. In other words the physical changes Adam passed along to subsequent generations.
(Note: Among some Christians these verses have long been very wrongly understood to mean that Adam became totally corrupt and alienated from God because of his sin, then passed on this fallen nature to all his descendants. See Calvinism)
As shown in the linked article it is entirely possible that Adam and Eve's epigenome underwent some drastic changes due to the first sin, the guilt that followed and the fact that their lives became infinitely more difficult away from the Garden of Eden. While we certainly inherit faulty gene function from our parents, it is only God who can reset the expression (behavior) of those genes after we make a conscious decision to turn back to Him.
In which case, it is entirely feasible that true Biblical repentance and a conscious decision to follow Christ results in God 're-setting' the altered epigenome which, in essence, would be a new birth from above.
See Original Sin or Epigenetics
What Does it Take To Be Born Again?
Paul's conversion very dramatically changed him from Saul of Tarsus who persecuted early Christians to Paul an amazingly effective teacher and evangelists who not only planted and nurtured many an early church but wrote two thirds of the New Testament. Although since then conversions have been considerably less spectacular, there are several crucial elements that have to be present in every genuine conversion.
1.) Awareness of the reality of sin, its consequences, and our need for forgiveness. And no, we are not all terrible people but nonetheless have to realize that every single one of us have fallen far short of God's standards. See Sin and Repentance
2.) An understanding of who Jesus is, what His death on the cross meant, and the reality of His second coming when He will judge the world. See Salvation and The Wrath of Gcd.
3.) A willingness to enthrone Jesus as Lord of your life. Few seem to realize that Jesus is called "Lord" over six hundred times in the New Testament and Savior a mere 24 times. In fact, 60% of the New Testament books never even once mention Jesus as Savior. See Salvation Part II
Finally there is one test for that can help determine whether a person's conversion is authentic or not. Anyone who is born of the Spirit will demonstrate a changed life. Salvation and eternal life do not come without anything being expected of us. To imagine that we can live our lives like the rest of the world, but still be welcome in God's presence, is little more than wishful thinking. The kingdom doesn't come cheap and regardless of what you may have been told, the Bible never once says ANYTHING about a "free gift". In fact, the word "free" has not been used anywhere in the New Testament in connection with salvation or God's gift to us. See Salvation - Part III
Also See What is Holiness?
The Experience Itself
When it comes to the new birth there is no one size fits all. Everyone's experience is different possibly connected to their individual temperament and/or current circumstances, emotional state, need etc.
Sudden or Gradual?
In the book of Acts conversions seemed to happen almost immediately. They heard what Jesus offered, accepted it, and were baptized. However, to be noted is that the Holy Spirit fell on the Roman centurion Cornelius and his family before they were baptized.
Sudden and immediate conversions do happen in our present age as well. Many people can pinpoint the day, the occasion, and even the time they were born again. However, for other people the awareness of their new relationship with God comes upon them very slowly taking days, weeks, or even longer. It can be likened to a very slow dawning of a new day.
For some being born again can be very emotional complete with tears of joy or even relief - an immediate sense of being released from guilt. For other it is a feeling of peace or joy or a sense of being loved. Yet others have a sense of finding meaning and purpose to life. And then there are those, like myself, for whom it is completely unemotional.
The following accounts are from Rev. Dick Tripp's article Born Again
In his book Essentials, historian David Edwards tells how Stott recalled the silent prayer he prayed as he knelt at his bedside in a Rugby School dormitory one Sunday night in February 1938. In a simple, matter-of-fact but definite way he told Christ that he had made rather a mess of his life so far; he confessed his sins; he thanked Christ for dying for him; and he asked him to come into his life. The sincerity of that prayer was evidenced by the note that Stott wrote in his diary next day, "He has come into my house and now rules in it."
C. S. Lewis, described his final step as follows:
I know very well when, but hardly how, the final step was taken. I was driven to Whipsnade one sunny morning. When we set out I did not believe that Jesus Christ is the Son of God, and when we reached the zoo I did. Yet I had not exactly spent the journey in thought. Nor in great emotion. "Emotional" is perhaps the last word we can apply to some of the most important events. It was more like when a man, after a long sleep, still lying motionless in bed, becomes aware that he is now awake.
Colleen Townsend Evans was an actress on the verge of finding success when offered the "big buildup" by a head producer in Hollywood, tells how she found instead real purpose in Jesus. She found him in a quiet undramatic way at a Christian Conference:
"I went for a walk and said, "God, if all this is true, if this is the answer and if you are the way, I just want to give my life to you...everything." There were no voices, no visions, but that was the beginning. I walked along the road that morning with a totally new life. Everything looked different, things smelled different, life was different, because I had found the meaning of life in the person of Jesus Christ".
IPS Note: In 1950, Colleen abruptly abandoned Hollywood and devoting herself to religion. She and began speaking at churches and Youth for Christ evangelistic events and served on the boards of several ministries, including the Christian College Coalition and World Vision and International Justice Mission.
Keith Millar, author of a number of significant books on Christian living, tells of his conversion as he sat in his car in the pinewoods country of East Texas in complete despair. He had been through training for Christian ministry in seminary, but had never known God personally. He says:
As I sat there I began to weep like a little boy, which I suddenly realized I was inside. I looked up towards the sky. There was nothing I wanted to do with my life, and I said, "God, if there is anything you want in this stinking soul, take it."... There wasn't any ringing of bells or flashing of lights or vision; but it was a deep intuitive realization of what it is God wants from a man which I had never known before, and the peace which came with this understanding was not an experience in itself. It was rather a cessation of the conflict of a lifetime. I realized then that God does not want a man's money, nor does he primarily want his time, even the whole lifetime of it a young Seminarian is ready to give him. God, I realized, doesn't want your time, he wants your will; and if you give him your will, he will begin to show you life as you have never seen it before.
US Senator, Mark Hatfield who was the United States senator from Oregon for 30 years and one of the most openly religious men in American politics at that time.
"I saw that for thirty-one years I had lived for self and decided I wanted to live the rest of my life only for Jesus Christ. I asked God to forgive my self-centered life and to make my life his own. Following Christ has been an experience of increasing challenge, adventure and happiness. Living a committed Christian life is truly satisfying because it has given me true purpose and direction by serving not myself but Jesus Christ.
Russian author and intellectual, Marcinkowski, spoke of "the deep indescribable quietness of eternity" and wrote, "an inexpressible joy brightened my soul."
D. L. Moody, the American evangelist, said of his experience:
"I thought the old sun shone a good deal brighter than it ever had before - I thought that it was just smiling upon me; and as I walked out upon Boston Common and heard the birds singing in the trees, I thought they were all singing a song to me. Do you know, I fell in love with the birds. I had never cared for them before. It seemed to me that I was in love with all creation".
"The appearance of everything was altered; there seemed to be, as it were a calm, sweet cast or appearance of divine glory in almost everything. God's excellence, his wisdom, his purity, and love seemed to appear in everything; in the sun, moon and stars; in the clouds and blue sky; in the grass, flowers, trees, in the water and all nature". See Calvinism
Dick Tripp adds (Emphasis Added)
However, whether this process is sudden or gradual is not the important issue. One woman, who shared faith in Christ with her husband, said, "I always tell people that I came to Christ with a big bang and Jim came with a slow burn." The real question is: Has it happened? At some point in each person's search for God, he gives them the Holy Spirit and they are reborn. This, by nature of the event, cannot be anything but sudden. Either we have received the Holy Spirit or we haven't. The Bible is clear about this. We don't have to know when it happens... However, it is important to know that it has happened. 
Popular Substitutes for Spiritual Rebirth
There are two things which people commonly trust in to make them acceptable to God, but which are no substitute for becoming a genuine disciple of the Lord Jesus Christ.
The fellowship of like minded believers can be immensely important providing an avenue for learning, encouragement, growing in our faith, not losing hope, etc.
Unfortunately, it is not always an simple matter to find a genuine Bible believing church. Too many have fallen by the wayside teaching doctrines directly derived from the occult (The Prosperity/Word of Faith Doctrines, Slain in the spirit, Contemplative Prayer, Labyrinths, etc). See Doctrines of Demons
And, even if we do find one that doesn't hold with outlandish beliefs and practices, it is very easy to simply fall into church membership without being a true and committed disciple of Christ.
Other more 'traditional' churches have all too often substituted human activity (great programs, thousands of books, wonderful music, 'conferences' galore, vigorous preaching) for God's power. Although the glory and presence of God is glaringly absent and the silence from Heaven is deafening people don't seek God because they are wholly convinced that they have already arrived. They are comfortable, complacent and lacking passion. Jesus had a name for it - "lukewarm".
Christianity is not alive and well in spite of loud declarations to the contrary. See Why The Fire Hasn't Fallen -
It is easy to suppose that doing good deeds can improve one's credit rating with God. However, the Scriptures are plain - good works, by themselves, cannot gain salvation and are certainly no substitute for a whole hearted belief in Christ and obedience to His commands.
For by grace you have been saved through faith; and that not of yourselves, it is the gift of God; not as a result of works, so that no one may boast. (Ephesians 2:8-9 NASB). Also See Titus 3:5-7.
On the other hand we should pay close attention to the number of times the Scriptures tell us that we will be judged, not by how much faith we have, but by what that faith produces. In other words, every person will be judged by the fruit they bear - their actions/deeds that came about as a result of their faith. As James said "But are you willing to recognize, you foolish fellow, that faith without works is useless? (James 2:20 NASB) See Myth of Faith Alone
Baptism Also note Baptism is a ceremonial ablution that a symbolizes a believer's union with Christ in His death and resurrection. It implies turning to Christ and away from the old life, consecrating oneself - body and soul - to God. Although baptism is not necessary for salvation (A topic in itself - See Baptism ) without any shadow of doubt, conversion and baptism are irrefutably linked. it does not say much for your conversion if your very first act is disobedience, that is of course, provided you have understood that baptism was commanded by our Lord.
However, it is not a substitute for the new birth - rituals cannot save us Without repentance and faith,.
Being re-born is not the end but merely the beginning.
Unfortunately, the problem is as John Piper says,
the evangelical church as a whole in America is apparently not very unlike the world. It goes to church on Sunday and has a veneer of religion, but its religion is basically an add-on to the same way of life the world lives, not a radically transforming power. 
He adds that it is a profound mistake to apply the term born again to describe professing Christians
"... whose lives are indistinguishable from the world, and who sin as much as the world, and sacrifice for others as little as the world, and embrace injustice as readily as the world, and covet things as greedily as the world, and enjoy God-ignoring entertainment as enthusiastically as the world" 
For some it will be a long journey and many will find it an arduous one. However, we need to keep our eyes on the prize.
The Anableps fish is commonly known as the Four-Eyed Fish. Despite the name, it doesn't actually have four eyes.. Rather the fish has two large, bulbous eyes positioned on the upper side of their heads and divided into an upper and lower section by a band of tissue. This unique arrangement enables the fish to lie just below the surface of the water yet see clearly both above and below them.
This provides a useful image for every born again Christian who needs to view both the spirit and material worlds at the same time keeping both in perspective. Like the Anableps we live in the murky waters of this world but everything we say and do has to be influenced by the one we see above us.
It is, quite simply, a matter of life and death.
See The Message of The Bible and Salvation
 Dick Tripp What Does It Mean To Be Converted Or Born Again. http://christianity.co.nz/2016/02/born-again/
 Michael Gryboski, Christian Post Reporter.
 Steven J. Cole. The Spirit-filled Life. https://bible.org/seriespage/lesson-44-spirit-filled-life-ephesians-518
 Dick Tripp What Does It Mean To Be Converted Or Born Again. http://christianity.co.nz/2016/02/born-again/
 John Piper. You Must Be Born Again. https://www.desiringgod.org/messages/you-must-be-born-again