Psychologists talk about two kinds of motivation: intrinsic and extrinsic. Intrinsic motivation is what drives you to do something regardless of whether you will receive a reward. Why do you spend an hour cleaning the inside of your stove? Nobody looks in there. Your intrinsic motivation compels you to do a thorough job. We all have it -- in fact, most people start out with the desire to excel at whatever they do. Extrinsic motivation is the drive to do something precisely because you expect to receive compensation, and it's the weaker of the two.

The interesting thing, according to psychologists, is that extrinsic motivation has a way of displacing intrinsic motivation. The very act of rewarding workers for a job well done tends to make them think they are doing it solely for the reward; if the reward stops, the good work stops. And if the reward is too low, workers might think, Gosh, this is not worth it. They will forget their innate, intrinsic desire to do good work. </quote> http://www.inc.com/magazine/20090101/how-hard-could-it-be-th...