Happiness is not about working the hardest; it's about having the most challenging work. Harvard prof Rosabeth Moss Kanter explains. "The happiest people I know are dedicated to dealing with the most difficult problems," Rosabeth Moss Kanter writes for HBR. Whether reversing schools' struggles, making unsafe water potable, or helping the terminally ill, "they face the seemingly worst of the world with a conviction that they can do something about it and serve others." Money acted as a scorecard, but it did not get people up-and-at 'em for the daily work.Kanter pulls in a number of anecdotes, including that of her friend, the Pulitzer Prize-winner Ellen Goodman.