Inner peace.

Shen : How did you find peace? I took away your parents, everything, I scarred you for life...
Po    : See that's the thing, Shen, scars heal.
Shen : No they don't... *wounds* heal.
Po    : Oh, yeah... what do scars do? They fade, I guess...
Shen : I don't care what scars do...!
Po    : You should, Shen. You got to let go of the stuff from past - because it just doesn't   matter! The only thing that matters is what you choose to be now. 

So, how to heal the scars? Or wounds? Or maybe that's true, like the wise men said, time heals all wounds?

Source: Kungfu Panda 2.