Are doctors who make mistakes villains? No, because then we all are. - Atul Gawande

When you are young and healthy, you believe you will live forever. You do not worry about losing any of your capabilities. People tell you “the world is your oyster,” “the sky is the limit,” and so on. And you are willing to delay gratification — to invest years, for example, in gaining skills and resources for a brighter future. You seek to plug into bigger streams of knowledge and information. You widen your networks of friends and connections, instead of hanging out with your mother. When horizons are measured in decades, which might as well be infinity to human beings, you most desire all that stuff at the top of Maslow’s pyramid — achievement, creativity, and other attributes of “self-actualization.” But as your horizons contract — when you see the future ahead of you as finite and uncertain — your focus shifts to the here and now, to everyday pleasures and the people closest to you.

In one of her most influential studies, she and her team tracked the emotional experiences of nearly two hundred people over years of their lives. The subjects spanned a broad range of backgrounds and ages. (They were from eighteen to ninety-four years old when they entered the study.) At the beginning of the study and then every five years, the subjects were given a beeper to carry around twenty-four hours a day for one week. They were randomly paged thirty-five times over the course of that week and asked to choose from a list all the emotions they were experiencing at that exact moment.
If Maslow’s hierarchy was right, then the narrowing of life runs against people’s greatest sources of fulfillment and you would expect people to grow unhappier as they age. But Carstensen’s research found exactly the opposite. The results were unequivocal. Far from growing unhappier, people reported more positive emotions as they aged. They became less prone to anxiety, depression, and anger. They experienced trials, to be sure, and more moments of poignancy — that is, of positive and negative emotion mixed together. But overall, they found living to be a more emotionally satisfying and stable experience as time passed, even as old age narrowed the lives they led.
The findings raised a further question. If we shift as we age toward appreciating everyday pleasures and relationships rather than toward achieving, having, and getting, and if we find this more fulfilling, then why do we take so long to do it? Why do we wait until we’re old? The common view was that these lessons are hard to learn. Living is a kind of skill. The calm and wisdom of old age are achieved over time.
Carstensen was attracted to a different explanation. What if the change in needs and desires has nothing to do with age per se? Suppose it merely has to do with perspective — your personal sense of how finite your time in this world is. This idea was regarded in scientific circles as somewhat odd. But Carstensen

amount of freedom you have in your life is not the measure of the worth of your life. Just as safety is an empty and even self-defeating goal to live for, so ultimately is autonomy.