You have to accept whatever comes and the only important thing is that you meet it with the best you have to give. --Eleanor Roosevelt
We can kick and scream and rail against circumstances, but we will have no peace (and no ability to change them) until we choose acceptance. Then we move on to "the only important thing."
"Always do your best." This is one of "The Four Agreements" as written by Don Miguel Ruiz. Our best is the highest functioning we are capable of at the time, and that changes from moment to moment. If you are ill, your best will be different from when you are healthy and vibrant. Your best will vary depending on whether you are well-rested or exhausted. Doing your best is not perfectionism, I repeat, NOT perfectionism. "Perfect" does not exist, not individually nor collectively. I'd offer that the 12-step programs refer to perfectionism as "the purest form of self-abuse." Contemplate that for a few moments.
So we meet whatever comes with our best and move on with serenity. It's a practice, and a very satisfying and "clean" way to live.