Memories are meant to fade : They're designed that way for a reason (idea)

That people change, and places change, and that it isn't always good to hang onto the past through artificial memories created by photographs, video, etc. Doing so hinders growth, and makes it harder to overcome new challenges.

Presented by Mace in the film Strange Days.

That is not to say though, that you should forget the past. Just don't be held there by material memories.