I could see that working but then I'm thinking bruised knuckles and that just hurts. I used to punch my leg then I decided why hurt me more than I've already been hurt.

Have you ever tried meditation to try to control your thoughts and drive them back? It's taken years of practice but most times if I can't drown mine out then I can replace them with better thoughts. Even if it's just the plot of a favorite movie I play it over in my mind. Or I listen to music in my head like my own private radio to drown out the thoughts I don't want.