This is my absolute favorite quote that I have ever read.
"You need only claim the events of your life to make yourself yours. When you truly possess all that you have been and done, which may take some time, you are fierce with reality." -Florida Scott-Maxwell.
It goes with my belief that regret (when it limits us) is not healthy. I always think we should just acknowledge that something may have been less than prime, and then we should move on. If we didn't like the situation that causes regret, we can just promise ourself to not do the same action, or get into the same situation again.
And, another good one...
"What we must decide is perhaps how we are valuable, rather than how valuable we are." -F. Scott Fitzgerald