“Satisfaction. The satisfaction that comes from achievement. From having worked and produced and accomplished. Adults need it the way babies need milk. And like milk, satisfaction has a shelf life. People can feed off past accomplishments for a couple of weeks, but their mood starts to sour after that. “I have developed the theory that adults wean themselves off the need to achieve as they move beyond middle age. By the time they’re seniors, they can sustain a positive attitude off the energy of past accomplishments. But as Immortals, we’re stuck with the achievement appetite of youth.”