When you have a negative emotion/story in your head that just keeps popping in your head over and over and over again, daily, sometimes even hourly, is it okay to just stamp it out and constantly replace the thought with something else that's more positive until it eventually goes away? Or do you HAVE to try to "figure it out" and see what purpose it's serving before letting it go? In my case, there's nothing logical to figure out and it's only hurting me. I honestly have no idea why I'm so obsessed with it.

What's the difference between letting go and repression? How do I know when it's appropriate to just think something else?