When I was 17, I read a quote that went something like: "If you live each day as if it was your last, some day you'll most certainly be right." It made an impression on me, and since then, for the past 33 years, I have looked in the mirror every morning and asked myself: "If today were the last day of my life, would I want to do what I am about to do today?" And whenever the answer has been "no" for too many days in a row, I know I need to change something.
Steve Jobs, Stanford University, 2005