Don't try to nit-pick and rationalize into a what-if scientific equation.
This is a faith based process just like any religion except it is not a religious experience.
People really screw themselves up when they start trying to understand, and especially prove, their religious beliefs by scientific methodologies.
1) Because ...
I am calm and free with no anger, accepting life on life's terms and I enjoy life in a spiritual way ...
I accept what has happened in the past with no resentment and do not replay perceived injustices against me ...
I look to the future with no fear and I have faith that I, with the help of my Higher Power, can deal with whatever the future brings.
2) Over a period of time and lots of meditation/prayer and because 1) took place.
3) Calming me down and revealing that my wants are based on my ego ... as I meditate and pray, I am able to look outside of my self-controlled desires to gain the wisdom to make the right choices.