The study1 analyzed data from 28,248 cancer patients enrolled in South Africa’s Discovery Health Medical Scheme. All participants were part of the Vitality health promotion program, which tracked their physical activity through fitness devices, gym visits, and organized events.

However, in this study, it was not happiness or another factor that was considered: It was the simple existence of a sense of purpose—which, like physical activity, can decline with age in some cases. Purpose, for many Americans in particular, can be tied to the roles we exist in during our lives, so it makes some sense that aging and the things that go with it, like retirement, may be tied to a loss of that feeling.