When you've given something your very best, rest easy, no matter what the outcome is.
Forget what others think. Only you know if you've given every ounce of energy and attention to what you faced. You can lie about your efforts to others, but you can't lie to yourself. Deep down, you know.
When you do your best, you can forget the rest.
As long as you tackle things to your full potential, cast off the doubt, what-ifs, anger, naysayers, and all the other crap that robs you of the joy in knowing you gave maximum effort to the matters at hand.
When you do this, hold your head high. Because that's how you win in any situation.