The document discusses how difficult it is for people to accurately predict how they will respond to future risks and challenges. It provides the example of a friend who achieved his goal of becoming a doctor against all odds, but is now disappointed in his career. People are poor forecasters of their future selves and tend to ignore important context when anticipating future situations. Investors in particular struggle to predict how fearful or greedy they will feel during market downturns or surges. The best approach is to use past behavior as a guide rather than trying to envision hypothetical future responses.