Champions aren't made in gyms. Champions are made from something they have deep inside them: A desire, a dream, a vision. They have to have last-minute stamina, they have to be a little faster, they have to have the skill and the will. But the will must be stronger than the skill.
Earliest attribution to Muhammad Ali found in: Reaching for Excellence: The Glory and Decay of Sport in India (Kalyani Publishers, 1979), p. 59