I tell the kids all the time that there are things that you can say and do that you can't take back. It's true. Sometimes we hurt people and there's nothing we can do to fix it. It's up to them to forgive us... or not.
The flip side of the coin is also true though. If you do something good, you can't undo it by doing something bad.
Give yourself credit for the good things you do and don't beat yourself up over the bad things. Learn from your mistakes for sure, but don't weigh them heavier than they need to be.
Your good deeds cannot be undone by your failures. So forget about where you've failed, get back up and go do something good today. Because that good can never be taken away.