It took me a lot of personal work, but I made peace with the fact that we are all on a big rock flying through the Cosmos at 40,000 km/h a long time ago. We are all gonna be gone one day. The entire Earth, gone. Our existence is meaningless in the grand scheme.
Worry about what you can control. Also, try and worry about today. If you worry about tomorrow too much, you'll miss the only day you can do anything. Today. Do your best to do what you can each day, the rest of it is all chance.