People are always telling me that I should "forgive myself" for past mistakes. What exactly does that mean and how do I do it?
We learn by trial and error, and the errors are made by us and others. We also learn by imagining experiences ("Gee, I wonder how it would feel to touch that hot stove—probably not too good"). But sometimes we viscerally learn by going ahead and blundering.
People might perceive that you are very harsh and self-critical when you make a mistake. We don't like making mistakes, and that's a good thing. However, we often go overboard and sometimes really get down on ourselves, others, or in the extreme, life in general.
Forgiving yourself means first accepting that you committed an error, but secondly, refusing to condemn yourself totally for having made it.
It is important to admit the gravity of the mistake. The error may be very bad, and admitting it to yourself is the first step toward improving the effects of the error. Forgiving yourself means accepting your human fallibility.
One of the great errors of the human-potential movement of the '70s and '80s is the idea of human perfectibility. Although perfection is a great and lofty goal, it can eternally frustrate us from actually producing worthwhile things—especially if you prevent yourself from trying new things because you'd have to feel so badly about a possible mistake.