A person is more continuous than their mood and less fixed than their biography.

You are not your mood and you are not your history. A bad afternoon does not tell you who you are, and neither does a list of things that happened to you, and identity sits somewhere between those two, more stable than the day and more mobile than the record. That middle position is easy to forget in either direction.

When you are low, resist reading it as a permanent finding. When you feel fixed by your past, notice how much you have already changed. Both errors are common and both are corrected by looking at a longer stretch than the one in front of you.