A string of bestsellers have alerted us to the importance of grit—an ability to persevere and control one’s impulses that is closely associated with greatness. But no book yet has charted the most accessible and powerful path to grit: our prosocial emotions. These feelings—gratitude, compassion, and pride—are easier to generate than the willpower and self-denial that underpin traditional approaches to grit. And, while willpower is quickly depleted, prosocial emotions actually become strong...