In piano performance, you never dwell on past mistakes. Once you've moved past that botched up section, or that measure where you hit only half the notes, you automatically forget the past, and continue forward with confidence. You never allow the mistakes previously in the piece to affect the rest of it. Seconds after you stumbled, you forget so completely, it’s like it never happened. At the end of the piece, no matter what, you pretend as though it was your best performance.
Apply this principle to your life, and guaranteed you won't be as paralyzed by your past.