There are three important things to know about the past. One, it's over. Two, you can't change it. And three, the only thing keeping it alive is the energy you put into holding on to it. Letting go of the past can be one of the most liberating events in your life. It means allowing what was to be what it was -- and also, what it was not. It doesn't necessarily mean forgetting, but it does mean forgiving -- both yourself and others.