I'm not a religious person, by any stretch of the imagination. Still, the Serenity Prayer is very useful. Whether you think of it as a prayer, or as self-talk, it's good stuff.
"God, grant me the serenity to accept the things I cannot change,
The courage to change the things I can,
And the wisdom to know the difference. "
Notice it doesn't say, "Grant me the serenity to blindly accept every wrong that comes my way." Just "the things I cannot change." The things you can change are dealt with in the next line.