When you win, you don't examine it very much, except to congratulate yourself. You easily, and wrongly, assume it has something to do with your rare qualities as a person. But winning only measures how hard you've worked and how physically talented you are; it doesn't particularly define you beyond those characteristics. Losing on the other hand, really does say something about who you are. Among other things it measures are: do you blame others, or do you own the loss? Do you analyze your failure, or just complain about bad luck? If you're willing to examine failure, and to look not just at your outward physical performance, but your internal workings, too, losing can be valuable. How you behave in those moments can perhaps be more self-defining than winning could ever be. Sometimes losing shows you for who you really are.