mh, journaling
I've run into this;
I know that even in my most miserable times I've had sparks of joy, memories I hold onto for years later; no matter how bad it gets, I can look forward to something being good. Whether I can look back at a chunk of my life as good or bad is very much about intensity and frequency.
I find that I'm conflating how happiness is around every corner in a difficult life, with how I'm frustrated by not getting big goals (confused both by how some of them are the societal standards, and how some might just be unlikely out the gate). Part of how happiness and success is nuanced.