Emerson was quoted at the end of The Eating Well Diet (Book Review: The Eating Well Diet by Jean Harvey-Berino). There were numerous other quotes in that book, another thing I liked about it.
Finish each day and be done with it. You have done what you could; some blunders and absurdities have crept in; forget them as soon as you can. Tomorrow is a new day; you shall begin it serenely and with too high a spirit to be encumbered with your old nonsense.
–Ralph Waldo Emerson