The Perfect Rewards and Incentives Program
Conditioning human behavior through reward is more complicated than most people realize. Giving a reward for the wrong reason, in the wrong way or even the wrong time, can actually reduce a person's enjoyment of a given task (See "Undermining children's intrinsic interest with extrinsic reward: A test of the 'overjustification' hypothesis," by Leper et al., or just Google "Overjustification Effect"). Essentially, if someone already has a high interest in a task, say painting for instance, providing a reward for completing that task can make it less fun and interesting because it's getting equated with work in the person's subconscious. The idea is that (for whatever reason) people associate rewards with work, and work is supposed to be something tedious and loathsome. Therefore, anything that gets rewarded must be work, and work is not supposed to be fun. So, when a person gets rewarded for doing something he or she already likes, the mind tells the person: "Hey! You were wrong this whole time. All that painting you've been doing wasn't actually fun—it was work in disguise!" There's more to it than that, involving concepts like cognitive dissonance and how the mind processes history both backward and forward instead of linearly, but that's the basic idea.