Reminds me of this:
Reb Zusha was laying on his deathbed surrounded by his disciples. He was crying and no one could comfort him. One student asked his Rebbe, "Why do you cry? You were almost as wise as Moses and as kind as Abraham." Reb Zusha answered, "When I pass from this world and appear before the Heavenly Tribunal, they won't ask me, 'Zusha, why weren't you as wise as Moses or as kind as Abraham,' rather, they will ask me, 'Zusha, why weren't you Zusha?' Why didn't I fulfill my potential, why didn't I follow the path that could have been mine."
If you compare yourself with others, you may become vain or bitter; for always there will be greater and lesser persons than yourself.
Full text on wikipedia: http://en.wikipedia.org/wiki/Desiderata#Full_text
A similar thought was formulated by Morihei Ueshiba: "There are no contests in the Art of Peace. A true warrior is invincible because he or she contests with nothing. Defeat means to defeat the mind of contention that we harbor within."