“Running is the source of my stamina. Early in my career I learned to run until I’m tired, then run more after that. The running I do before the fatigue and pain is just the introduction. The real conditioning begins when the pain comes in; then it’s time to start pushing. And after that I count every mile as extra strength and stamina. The reserve tank. What counts in the ring is what you can do after you’re tired.”

- Muhammad Ali