If you've ever looked closely at the walls of your elementary school, your dentist's office, or the lobby of any midsized corporation, you already understand everything you need to know about motivation. Chances are those locations have several posters featuring generic photos and a tidy inspirational message, such as “Believe you can, and you're halfway there,” “The harder you work, the luckier you get,” and the perennial standby, “There is no ‘I’ in ‘TEAM’.” Understanding motivation, it seems, is as simple as spending $9.99 and getting four thumbtacks.

But if that seems too simple, you might be willing to pay more for the advice of an “expert.” Search the Internet for the phrase “hire a motivational speaker” and you'll get hundreds of thousands of results. There are numerous agencies and individuals ready to tell you about everything from the secrets of innovation to the keys to success to what the future holds, all for a fee, of course. If you'd rather not sit through a 45-minute presentation, many speakers will happily sell you an elaborate set of workbooks and videos to improve your motivation on your own time.

By now you're probably guessing that understanding motivation is not as simple and straightforward as poster manufacturers and well-meaning hucksters make it seem. Understanding a person's motives means answering a core question of psychology: Why do people do what they do? Your own experience tells you that the reasons for a behavior can be a varying and interactive set of biological, psychological, cultural, and interpersonal forces. What's more, the enormous range of people's thoughts and behaviors means that offering any single answer to the “why” question is likely to come up short.

For many decades, the study of motivation was dominated by a focus on biological drives, such as those to acquire food and water, to have sex, to seek novelty, and to avoid cold and pain. But drive theories do not account for the full complexity of human motivation, because people are conscious creatures who think and plan ahead, set goals for themselves, and plot strategies to reach those goals. People may have a drive to eat, for instance, but that information doesn't tell us why some individuals will go on hunger strikes to protest injustice.

In this chapter, we will examine four central areas of human motivation: food, love, sex, and achievement. We will also see how happiness and well-being are affected by the kinds of goals we set for ourselves.