Creativity often consists of merely turning up what is already there. Did you know that right and left shoes were thought up only a little more than a century ago?
Bernice Fitz-Gibbon 

Cudgel thy brains no more about it.
William Shakespeare  - Hamlet

Difficulties are meant to rouse, not discourage.
William Ellery Channing 

Diligence is the mother of good luck.
Benjamin Franklin (1706-1790) 

Do not go where the path may lead, go instead where there is no path and leave a trail.
Ralph Waldo Emerson (1803-1882) 

Do or do not. There is no try.
Yoda  , character in the movie, The Empire Strikes Back

Do well and you will have no need for ancestors.
Voltaire (1694-1778) 

Do what you can, with what you have, where you are.
Theodore Roosevelt 

Do your damnedest in an ostentatious manner all the time.
George S. Patton, General (1885-1945) 

Don't be afraid to give up the good for the great.
Kenny Rogers