I came across this quote in an article on the huddle and just wanted to archive it here.
The best players treat competition as an opportunity for them to measure their greatness. Imagine a set of scales: you and your team are on one end, your opponents on the other. The fulcrum is made of the rules of the game. If you break the rules, you unbalance the scales and lose the accuracy of the measurement. If you belittle your opponents, you lose your counterweight, and diminish the meaning of any success you might have. (Your win doesn't mean very much if "they suck.") In order to evaluate yourself and your team honestly—that is, to have self-respect—you have to treat your opponents and the rules with respect, and even gratitude. Without them, you can't measure your greatness.