Ralph Waldo Emmerson

Finish every 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 cumbered with your old nonsense. 
This day is all that is good and fair. 
It is too dear, with it's hopes and invitations, 
to waste a moment on the yesterdays.

Ralph Waldo Emmerson