This is what Jesus has said about the matter:
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 are a teacher come from God; for no one can do these signs that You do unless God is with him.”
Jesus answered and said to him, “Most assuredly, I say to you, unless one is born again, he cannot see the kingdom of God.”
Nicodemus said to Him, “How can a man be born when he is old? Can he enter a second time into his mother’s womb and be born?”
Jesus answered, “Most assuredly, I say to you, unless one is born of water and the Spirit, he cannot enter the kingdom of God. 6 That which is born of the flesh is flesh, and that which is born of the Spirit is spirit. Do not marvel that I said to you, ‘You must be born again.’ The wind blows where it wishes, and you hear the sound of it, but cannot tell where it comes from and where it goes. So is everyone who is born of the Spirit.” (John 3:1-8)
What does this mean? It means that we have let go of control of our lives and given that over to the Holy Spirit. We have placed all our faith in Jesus Christ for our salvation and eternal life with God.
It means that we have died to ourselves. The Apostle Paul writes:
I have been crucified with Christ; it is no longer I who live, but Christ lives in me; and the life which I now live in the flesh I live by faith in the Son of God, who loved me and gave Himself for me. (Galatians 2:20)
It means that we are now led by the Spirit of God and not our flesh:
Therefore, brethren, we are debtors—not to the flesh, to live according to the flesh. For if you live according to the flesh you will die; but if by the Spirit you put to death the deeds of the body, you will live. For as many as are led by the Spirit of God, these are sons of God. (Romans 8:12-14)
Does it mean that we have our ticket punched for heaven? By no means! We read in the Book of Hebrews:
Let us hold fast to the confession of our hope without wavering, for he who has promised is faithful. And let us consider how to provoke one another to love and good deeds, not neglecting to meet together, as is the habit of some, but encouraging one another, and all the more as you see the Day approaching.
For if we willfully persist in sin after having received the knowledge of the truth, there no longer remains a sacrifice for sins, but a fearful prospect of judgment, and a fury of fire that will consume the adversaries. (Hebrews 10:23-27)