There is a Nietzsche quote that always pops in to my mind when I'm in the depths of introspection.
"And when you gaze long into an abyss the abyss also gazes into you."
This is the point where I instigate the Don't Overthink It Protocol (AKA: DEFCON 3), which consists of the following...
- Accept what you can not control;
- Distract yourself with activities;
- Read a LOT;
- Plan things to look forward to; and
- Forgive the person who put you here.
Saying this out loud always helps me. It isn't a silver bullet but it is an easing of the melancholy.