It’s also important to realize that even if people have a fixed mindset, they’re not always in that mindset. In fact, in many of our studies, we put people into a growth mindset. We tell them that an ability can be learned and that the task will give them a chance to do that. Or we have them read a scientific article that teaches them the growth mindset. The article describes people who did not have natural ability, but who developed exceptional skills. These experiences make our research participants into growth-minded thinkers, at least for the moment - and they act like growth-minded thinkers, too.

In psychology, expanding our concerns and efforts beyond our own lives is called “generativity” and it’s a key to unlocking the vibrancy and excitement of midlife. Among Harvard Study participants, the happiest and most satisfied adults were those who managed to turn the question “What can I do for myself?” into “What can I do for the world beyond me?” John F. Kennedy—himself a Harvard Study participant—came to understand this well in his own midlife. He offered not just political, but emotional and developmental guidance when, as president, he said, famously, “Ask not what your country can do for you, ask what you can do for your country.” When asked at the end of their lives, “What do you wish you’d done less of? What do you wish you’d done more of?” our Study participants, male and female, often referenced their middle years, and regretted having spent so much time worrying and so little time acting in a way that made them feel alive.

That said, there are three prevalent sources of fuel for the inner fire across the vastly different lives in the study. In addition to love of the doing, the two others are:

Extend Out/Circle Back: This is a continuous dynamic process of extending yourself— growing, learning, experimenting, expanding capabilities, discovering new encodings— while simultaneously drawing upon encodings discovered and capabilities developed earlier in life.

By studying some of the most beautiful examples of people whose latent potential popped into view when they came into frame, I became increasingly attuned to seeing and sensing the encodings and fire of those around me.

Then one day, I woke up to realize that my entire emotional state had changed, not just in my work, but across my entire life. Instead of feeling frustrated with what people are not, I’d made a monumental shift to feeling grateful for what they are. I wish I’d made this shift decades earlier but as the Supreme Court Justice Felix Frankfurter pointed out, “Wisdom too often never comes, and so one ought not to reject it merely because it comes late.

By its very nature, this study relies on people with highly visible accomplishments. I worry that some readers might misinterpret this as an implicit worthiness hierarchy that valorizes achieving fame over taking more unseen paths. I also worry that some of the people in the study can feel so unapproachable in what they made of their lives that readers might discount the relevance of learning from them, or be left wondering, “Well, their lives are interesting, but could I ever do what they did?” I share that feeling. Studying Charles Colson made me feel somewhat intimidated by the standard he lived to after prison.