Muhammad Ali — American Athlete born on January 17, 1942,

Muhammad Ali is an American former professional boxer, generally considered among the greatest heavyweights in the sport's history. A controversial and polarizing figure during his early career, Ali is now highly regarded for the skills he displayed in the ring plus the values he exemplified outside of it: religious freedom, racial justice and the triumph of principle over expedience. He is one of the most recognized sports figures of the past 100 years, crowned "Sportsman of the Century" by Sports Illustrated and "Sports Personality of the Century" by the BBC... (wikipedia)

If you live long enough, you'll make mistakes. But if you learn from them, you'll be a better person. It's how you handle adversity, not how it affects you. The main thing is never quit, never quit, never quit. William J. Clinton
Darkness comes. In the middle of it, the future looks blank. The temptation to quit is huge. Don't. You are in good company... You will argue with yourself that there is no way forward. But with God, nothing is impossible. He has more ropes and ladders and tunnels out of pits than you can conceive. Wait. Pray without ceasing. Hope. John Piper
If you believe in yourself and have dedication and pride - and never quit, you'll be a winner. The price of victory is high but so are the rewards. Paul Bryant
Success seems to be connected with action. Successful people keep moving. They make mistakes, but they don't quit. Conrad Hilton
The way to get started is to quit talking and begin doing. Walt Disney