Just came across this in a book and found it quite soothing
"Finish each day and be done with it. You have done what you could. Some blunders and absurdities no doubt crept in; forget them as soon as you can. Tomorrow is a new day; begin it well and serenely and with too high a spirit to be encumbered with your old nonsense."
(Ralph Waldo Emerson - who also said "Sometimes a scream is better than a thesis.")