You see, I was a dedicated nail biter for decades. I bit them until they were bloody and sore, then did it again and again and again. All day, every day. To my shame, my terrible example influenced my daughters to do likewise.
(This is the hand and these are the nails of a woman who tried and tried to stop chewing herself to injury for years, and each time she failed she felt lower than the last time until finally she convinced herself that her hands were just ugly like the rest of her.)
But now, look! I did it! I quit mutilating myself. So whenever I feel worthless and incapable, I look at my hands to remind me that I did this.
And if I can do this, I can probably do other things, too.