Last summer, my sister, Dr. Mary Crossan, and I had a long, lingering conversation about the intersection between her research on leader character and mine in sustainable happiness. We were both on vacation and enjoyed the opportunity to catch up on each other’s work. It was a pivotal moment in our discussion when Mary asked me what kind of person is likely to choose sustainable happiness. Given the various options and pressures that individuals have on a day-to-day basis, what motivates one person to engage in sustainable behavior and another person, who may be fully aware of environmental consequences, does not? She pressed further with questions about what kind of person will care deeply enough about other people or even future generations in order to embrace sustainable happiness in a meaningful way. She explained that in her view, who that person is-the choices that they make-will ultimately be influenced by their character.