Returning Thoughts!

I remember awhile back you mentioned you had a re-occurring thought in your morning download something like “I shouldn’t have said that”, and you had to catch your brain doing that.
Do these “re-occurring thoughts” ever go away? Why do they come back? Can some thoughts that keep re-occurring be like an addiction to the “feeling” that they produce? If I have been so conditioned to “feeling” a certain way, how long will it take before the “better feeling” becomes the norm?