If you were to ask someone what their best and worst memories are/were, most people could probably tell you, and in detail.
Although we like to focus on the ones that are happy, fun, exciting, and loving, there may be others that we would like to forget, yet somehow can't.
Maybe it's the loss of a loved one, or being treated poorly by someone, or being abused physically or emotionally, being in an accident, seeing something that was disturbing, losing a job, etc.