What is human well-being? Valerie Tiberius argues that our lives go well to the extent that we succeed in terms of what matters to us emotionally, reflectively, and over the long term. In other words, well-being consists in fulfilling or realizing our appropriate values over time. In the first half of the book, Tiberius sets out the theory of well-being as value fulfillment. She explains what valuing is and what it is to fulfill values over time. In the second half of the book, she applies the theory to the problem of how to help others, particularly our friends. We don't always know how to provide the help we know others need; but we also have the problem of knowing what help they need in the first place, and this is a problem that requires ethical thinking. Tiberius argues that when we want to help others achieve greater well-being, we should pay attention to their values. This entails attending to how others' values fit together, how they understand what it means to succeed in terms of these values, and how things could change for them over time. Being a good and helpful friend, then, requires cultivating some habits of humility that overcome our tendency to think we know what's good for other people without really understanding what it's like to be them.