what are the best ways to stop ruminating about bad old experiences in one's life?

I'm not sure if this is an answer, i relate to the question. I have had psych sessions which are about things that i experienced in the past and present. I think will alot of the stuff i have either accepted as past and not relevant now or i have found an answer to something, or i have just managed to find a inner peace with it. But there is so much more that goes on in my head about old stuff, especially when i finally try to go to sleep and i lay there and Bang, they all come back to keep me awake.

**Learn to forgive yourself.** Let the damn old baggage go. The past is the past, dont let ruin your progress to become a better person you wish to be.