Suppose that you’re very athletic. For example, you might like to run, swim, play volleyball, or bike. You would like to perform better at your next competition. Perhaps you want to run a 5-kilometer race 1 minute faster or perhaps you want your team to advance further in a team sports competition, like volleyball. What concept can you use from this chapter to design your training program? Hint: This question is not about using concepts like markets, positive or normative analysis, or assuming that people act rationally, but there is one concept introduced in this chapter that is applicable to improving your athletic performance.