Don't torture yourself with your own thoughts.
The thoughts are just thoughts, and we have all struggled with this. Distraction is the best thing. Take a walk, clean out a drawer, write a poem, read a magazine article, come on here and read, go to the library. There are lots of ways to distract. Obsessive thinking about unhealthy things is - unhealthy.
You can change your thoughts. Have you tried meditation or yoga? It helped me a lot.