I was a freshman in college when an adult (I wish I could remember who) gave me a great piece of advice because I was always worrying about everything: No experience is bad as long as one learns from it, turn a negative thing into a positive thing. If you make a mistake and you understand why it was a bad choice, etc., then you are already smarter than you were yesterday. Worrying about things you can't change is a waste of time, you can only change what you do in the future.
I thought that was a wonderful piece of advice and I've always tried to see the positive side of everything. I still analyze situations that happen to me, and I might kick my own ass mentally a few times, but I try not to spend too much time dwelling on them. To do that, reinforces negative feelings that one has about one's self, and that isn't good. I analyze the situation to find out what I can learn from it. This also applies to things that happen to me that have nothing to do with a mistake that I made. Occasionally, it is very hard to learn something from those situations. I can see the positive things that were the result of the worst thing that ever happened to me, such as learning to trust my instincts about people regardless of what anyone else says, and finding out how truly strong I am, among other things.