Positive psychology describes three levels of happiness, and they get harder to reach and longer lasting as you go. Pleasure is easy and gone quickly. Passion runs deeper, because you care about the work itself. Purpose sits at the top, the sense that you belong to something much larger than yourself, and anyone who spends a summer shaping how children treat other people is squarely in that category.
This is the short version. The full lesson, with the story behind it, is in the book.
Take The Summer Camp MBA with you, or get the field notes by email while you work through the lessons here.