You are doing your best only when you are trying to improve what you are doing

We do what we can, and then make up a theory to prove our performance the best.

We do what we must, and call it by the best names we can, and would fain have the praise of having intended the result which ensues.

A man is relieved and gay when he has put his heart into his work and done his best

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.

Write it on your heart that every day is the best day in the year.