To change who you are you must strike a balance between peace and progress.
Certain goals require a certain character to be achieved.
Think of who you are, your concept of self, as an intellectual structure you've built with time.
When you remodel a house, do you go straight for the foundation? Or do you start with a small cosmetic issue so the entire house doesn't come crashing down?
When you start chiseling away at a slab of marble, do you smack with your hammer as hard as you can? Or do you make small, calculated taps so you don't turn them to dust?
The same concept applies to changing who you are.