First, why we need to attain it:
"Jesus answered and said unto him, Verily, verily, I say unto thee, Except a man be born again, he cannot see the kingdom of God." John 3:3
Here is how it is explained:
"Whosoever believeth that Jesus is the Christ is born of God: and every one that loveth him that begat loveth him also that is begotten of him." I John 5:1
We were all born to our natural mother but we were all born dead because our parents were dead, were they not?
"But of the tree of the knowledge of good and evil, thou shalt not eat of it: for in the day that thou eatest thereof thou shalt surely die." Gen 2:17
"And when the woman saw that the tree was good for food, and that it was pleasant to the eyes, and a tree to be desired to make one wise, she took of the fruit thereof, and did eat, and gave also unto her husband with her; and he did eat." Gen 3:6
So then to God they were dead even though they continued to walk around and talk and also had children and acted among themselves as if they were alive. Would not the children of dead people also be dead? That's you and me. For this reason God sent His Son so that we could be born again this time to the ral Life that Jesus brought for us...
So where do we go from being born again? How about overcoming the world as Jesus did?
"For whatsoever is born of God overcometh the world: and this is the victory that overcometh the world, even our faith" I John 5:4
Jesus did this, [overcame the world] and He paid the price to make it possible that we also may overcome the world:
"These things I have spoken unto you, that in me ye might have peace. In the world ye shall have tribulation: but be of good cheer; I have overcome the world." John 16:33
The world that Jesus overcame was NOT planet Earth as we should be able to see by looking around us. The world he overcame was the one within his own flesh which tempted him to sin.
"For all that is in the world, the lust of the flesh, and the lust of the eyes, and the pride of life, is not of the Father, but is of the world." I John 2:16
He overcame all of those attractions which when followed lead a person to sin. He made it possible for you and I to also overcome the world, our own little world, within each of us, of the "lust of the flesh, the lust of the eyes & the pride of life". One of rewards for us doing that is shown here:
"He that hath an ear, let him hear what the Spirit saith unto the churches; To him that overcometh will I give to eat of the tree of life, which is in the midst of the paradise of God." Rev 2:7
When we are able to and do eat of the "tree of Life", the one that Adam and Eve skipped in Eden then we'll understand what Jesus meant here:
"The thief cometh not, but for to steal, and to kill, and to destroy: I am come that they might have life, and that they might have it more abundantly." John 10:10