One of the consistent claims of books like these is that happiness is associated with all sorts of good life outcomes, including—most promisingly—good health.
It does not include important factors such as environmental quality or education outcomes–all things that contribute to a person's sense of well-being.
One study found that volunteer work enhanced all six aspects of well-being: happiness, life satisfaction, self-esteem, sense of control over life, physical health, and depression.
People whose levels of happiness and meaning line up, and people who have a strong sense of meaning but are not necessarily happy, showed a deactivation of the adversity stress response.
In previous cases, McMillan has found some of these patients were happy, had a sense of humor and wanted to live despite previous court applications to withdraw life support.
Twenge's team's analysis of the answers confirmed the earlier, well-established wellbeing climb, with scores rising across the 1990s, and into the later 2000s.
Since then, interest in the U-bend has been growing. Its effect on happiness is significant-about half as much, from the nadir of middle age to the elderly peak, as that of unemployment.