Have you ever wondered why you often regret your choices? In Stumbling on Happiness, award-winning Harvard professor Daniel Gilbert offers an explanation for what are, in his view, unavoidable poor decisions: You fabricate a large part of your reality—your memories of the past, perception of the present, and vision of the future. When you then use these inaccurate perceptions of the future, present, and past to make choices about what to do in the future, your choices are often poor and hinder future happiness.

In this guide, we’ll walk through Gilbert’s thesis, describing how your brain works and how its fabrication of reality leads you to make six specific types of bad decisions about your future. We’ll also link Gilbert’s ideas to other, related areas of human cognition. Finally, while Gilbert claims you can’t counteract your tendency to make poor decisions about your future, we’ll offer suggestions on how to improve your decision-making as much as possible.