Earlier quoted context omitted.
I'm personally big on the Serenity Prayer: God grant me the serenity to accept the things I cannot change; courage to change the things I can; and wisdom to know the difference. Total atheist, so maybe I should replace the word "God" with "Brain" or something.
You could quote Epictetus instead. He talks quite a bit about that http://classics.mit.edu/Epictetus/epicench.html
Or, the tldr; version, i.e. the Serenity Prayer. :)