Why do we put off starting a project even when we know we will regret it later? Why might you turn down a few dollars of free money just because the offer feels unfair? Standard economics often pictures us as flawless calculators, always choosing what maximizes our own payoff. This chapter brings psychology into the picture. You are going to see that we are human — with limited attention, a deeply ingrained sense of fairness, and a powerful urge to favor today over tomorrow. These insights give us a richer, more realistic map of how people actually make choices.