Persistence

From the book The Best of Success, compiled by Wynn Davis:

Persistence -  The power to hold on in spite of everything, the power to endure - this is the winner's quality. Persistence is the ability to face defeat again and again without giving up -- to push on in the face of great difficulty, knowing that victory can be yours. Persistence means taking pains to overcome every obstacle, and to do what's necessary to reach your goals.

"I do not think there is any other quality so essential to success of any kind as the quality of perseverance. It overcomes almost everything, even nature."
   -  John D. Rockefeller

"History has demonstrated that the most notable winners usually encountered heartbreaking obstacles before they triumphed. They won because they refused to become discouraged by their defeats."
   -  B.C. Forbes

"Most people give up just when they're about to achieve success. They quit on the one yard line. They give up at the last minute of the game one foot from a winning touchdown."
   -  H. Ross Perot

"Success is failure turned inside out,
The silver tint of the clouds of doubt,
And you never can tell how close you are,
It may be near when it seems so far.
So stick to the fight when you're hardest hit,
It's when things seem worse,
That you must not quit."
   -  Unknown

"Nothing in the world can take the place of persistence. Talent will not; nothing is more common than unsuccessful men with talent. Genius will not; unrewarded genius is almost a proverb. Education will not; the world is full of educated derelicts. Persistence and determination alone are omnipotent."
   -  Calvin Coolidge

Winners master persistence.