These are some quotes I like a lot:

    Never give in, never give in, never, never, never, never—in nothing great or small, large or petty—never give in except to convictions of honor and good sense.    [Sir Winston Churchill, Harrow School, October , 1941]

    I want to be thoroughly used up when I die, for the harder I work the more I live. I rejoice in life for its own sake. Life is no "brief candle" to me. It is a sort of splendid torch which I have got hold of for the moment, and I want to make it burn as brightly as possible before handing it on to future generations.     [George Bernard Shaw, Man and Superman]

   The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood; who strives valiantly; who errs and comes short again and again, who knows the great enthusiasms, the great devotions, and spends himself in a worthy cause; who at the best, knows the triumph of high achievement; and who at the worst, if he fails, at least fails while daring greatly, so that his place shall never be with those cold and timid souls who know neither victory nor defeat.     [Ovid , The Metamorphoses]

       

   "Nothing is so strong as gentleness and nothing is so gentle as real strength."    [St. Francis de Sales]

   "Immature love says: 'I love you because I need you.' Mature love says 'I need you because I love you.'"      [Erich Fromm]

A few from lesser mortals:

    I would rather crash in flames than never to have flown. [Russ Walden]

    Good advice regarding explosive devices and certain men:  If you can't read the markings -- don't push the buttons.        [Russ Walden]

    You've got to learn to laugh at life its ownself.  [Dan Jenkins]

      Real friends and true lovers don't keep score.    [Russ Walden]

    Glue joints have to set for a time to achieve their full strength.          [Jim Beasley]
 
For an excellent collection of quotes, try Slim's Quote Page.