Repressed Memories
Motivative forgetting is a very good way to forget repressed memories. Motivative forgetting is what Sigmund Freud called repressing memories. The reason we repress memories is because we have to provide protection for ourselves so that we do not become depressed or have any form of anxiety. This is because we usually repress memories that are horrible and were very tramatic in our past. For example if you were to be molested as a child you would try to repress this memory so you didn't have to deal with future saddness from them. Although we try to forget these things repressed memories are still in our unconcious mind producing anxiety. You are unable to get away from tramatic memories even if you try to forget them.