The thing that helped me was "let go or be dragged".
Death will happen whether I stress out about it or not. Stressing about it just contaminates the time you have. So I gradually learned to focus more on the "isn't existence weird?!" than "death is coming". And when you really get into the swing of it, your limited time becomes timeless.
I've had a long period of writer's block, regarding songwriting. So I decided to invent a language, with a backstory of the peoples who spoke it. It's a real challenge but exciting to see a language form right in front of you! And since I've been focusing so hard on the language, I've been writing some really fresh sounding music, and enjoying the songwriting process again. I guess I just needed to stop fussing over the music so much.