I have never dwelt on the past. Some times its a problem as family members or people I have known most of my life will say, "remember when such and such happened " ? I usually say NO.
I did go through periods of depression and then realised it was all based around the future. No, not death, more about getting old and not being able to to do what I could.
Now I just refuse to let my brain entertain the thoughts and I'm happy.