Negative Programming

Have you ever noticed yourself getting stuck in a negative thinking loop,where you keeping going over some mistake that you made or some hurtful remark soneone has made to you or about you? You just keep thinking of what you should have done or said that was better than what you actually did or said. It's like a part of you thinks you can change the past if only you keep thinking about it. You even realise that trying to change something that has already happened is a really crazy idea, but you keep doing it.
I've spent the past 2 and 1/2 days doing just that, knowing the futility, knowing that the smart thing to do is take what you've learned from the experience, then let it go. I know that letting go can be a little hard sometimes, but you just need to be persistant.
I don't usually hold on to something quite that long and I was upset with myself for doing it this time. I really let an incident at work almost throw me into a major depression. I guess since my private life is so unstable right now, it really bothered me to have my work life upset too, especially since it had been going pretty well.
I'm pulling myself out of my funk by focusing on the fact that there's no one single event that defines me unless I allow it to. We are more than single events or criticisms. We are more than our looks and more than any single deed that we may do, and we are all loved by God,just for existing.