Reading Forgiveness by Iyanla Vanzant - it's a 21 day step by step approach to forgiving. An interesting, useful exercise to go through. It strongly encourages journaling every day as part of the process.
Day 1 was about forgiving yourself for all the oh-so-human mistakes you might have made during life. We're all human, we all make mistakes. Learn the lesson, and focus on doing better. The beating-yourself-up over a past that can't be changed saps energy that could be used to make better choices going forward.
Easy to consider logically, but harder to put into practice. Still, her point is to work on it. Each time you work on it you get a bit better, and all that energy you free up can now be used for good purpose.
Do you beat yourself up over past mistakes? Can you try to release even a portion of that emotion and to accept you have learned from it?