If you are not big enough to lose, you are not big enough to win.
 Walter Reuther

If you chase two rabbits you will lose them both. 
Native American saying

We didn’t lose the game; we just ran out of time. 
Vince Lombardi

In the end, it’s extra effort that separates a winner from second place. But winning takes a lot more that that, too. It starts with complete command of the fundamentals. Then it takes desire, determination, discipline, and self-sacrifice. And finally, it takes a great deal of love, fairness and respect for your fellow man. Put all these together, and even if you don’t win, how can you lose?
I don’t remember too much about the tournaments I lose. 
Jack Nicklaus

"When you lose, do not lose the lesson" 
Dalai Lama

"It’s what you get from games you lose that is extremely important."
 Pat Riley

"I will tell you how to become rich. Close the doors. Be fearful when others are greedy. Be greedy when others are fearful."
 Warren Buffet

"The ballplayer who loses his head, who can’t keep his cool, is worse than no ballplayer at all." 
Lou Gehrig

"You win a few, you lose a few. Some get rained out. But you got to dress for all of them."
 Satchel Paige

It’s what you get from games you lose that is extremely important. 
Pat Riley

"The general who wins the battle makes many calculations in his temple before the battle is fought. The general who loses makes but few calculations beforehand." 
Sun Tzu

"If you can’t accept losing, you can’t win." 
Vince Lombardi

"To win at marriage, learn to lose Gerry Spence
The winners in life think constantly in terms of I can, I will, and I am. Losers, on the other hand, concentrate their waking thoughts on what they should have or would have done, or what they can’t do."
 Dennis Waitley

"Many of life’s failures are people who did not realize how close they were to success when they gave up."
 Thomas Edison

"Praise often turns losers into winners."
 Author Unknown

"I never expect to lose. Even when I’m the underdog, I still prepare a victory speech. H. Jackson Browne