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By doing things when you are too tired, by pushing yourself farther than you thought you could - like running the track after a two-hour practice - you become a competitor. Each time you go beyond your perceived limit, you become mentally stronger.

Pat Summitt (1999). “Reach for the Summit”, p.151, Crown Business
By doing things when you are too tired, by pushing yourself farther than you thought you could - like running the track after a two-hour practice - you become a competitor. Each time you go beyond your perceived limit,