People do not work for “nothing,” but what they do work for is often not just the pay they receive. Rather, they may work for the pleasure they find in their working activities, a pleasure that Juster has found to be generally greater than people's pleasures in their leisure activities. They may work because meeting the challenges at work increases their sense of personal control, or out of a sense of duty, or because of a pressing need to achieve some high standard of excellence. Wherever their motives may be, people evade the market's focus on exchange, for these motives are satisfied by internal rewards that do not depend upon exchanging money for work. When people work for these self-rewards and not for any apparent external rewards, they are said to be working because of intrinsic motivation and thus working for intrinsic rewards.

Part VI is devoted to an exposition of the nature of such motivation, the kinds of internal self-rewards enlisted, and the consequences for the market of work not motivated by market rewards. These consequences are substantial. In the first place, they destroy the formula on which economists rely: The utility of pay is compensation for the disutility of work. Where work is a positive utility, this formula clearly will not do. Then, substantively, these intrinsic rewards make it impossible for levels of pay to serve as the allocators of human resources, thus upsetting the calculations that are the guarantors of efficiency in the market.