The brain is a muscle that must be exercised to reach its full potential. Start out small, with consistent rests in between. Pushing limits after each recovery, bit by bit. Like every exercise the pain that follows can be excruciating . so not too fast or you will get hurt, in some cases irreversible. slow and steady, with good pacing you will get there. 

Breaking down the walls, that you hated, that once upon a time defined you. 

May God bless you the mental strength and the will to bear through it