Good things of the past

So, today I was thinking about how most people only remember the good as time goes on about the past. At every waking moment, we are feeling at our strongest and the most that we can. It is what we do and how we feel that defines us. All the bad feelings that are happening in one moment, will consequently be gone the next. Now, we remember the previous moment, and that it hurt. But say one year from now, we see the happy moments; the moments we laughed at and the ones where we had the most joy. Most people base their decisions on what is happening now, and not then. If each moment is different, than was the bad we were feeling in the moment the right way to affect our decisions? Should it come from the good moments, the moments that we cherish and want to have memories of? Perhaps we should base our decisions, thoughts, and feelings on a series of past events. If you take the good and the bad, but tend to forget the bad, are you more apt to give someone another chance? Did God give us the sense to let some unhappy memories go so that we can forgive, or try to make things right again?
Just some thoughts~