It's so simple it's hard to really appreciate. Accepting what is and acknowledging that all you can do is your best and other mindful practices can really help. Easier said than done. I'd highly recommend the Healthy Minds app as a nice, no cost place to start learning. It grew out of a University of Wisconsin program and, as far as I know, is funded by donations and grants.

Healthy Minds https://hminnovations.org/meditation-app