Psychologists also remind us that boredom is a more fertile mother of invention than necessity, and that it can stimulate very un-Nietzschean pro-social thoughts as well as a heightened sense of self-awareness, a perspective that is theologized in Zen Buddhism.

In study after study, high workplace stress has been shown to inhibit creativity, whereas “when people were feeling more positive, they were more likely to be creative,” says Teresa Amabile, Harvard Business School professor and author of The Progress Principle.

Boredom can be a useful tool for a psychoanalyst. It can be a sign that the patient is avoiding a particular subject; that he or she is unable to talk directly about something intimate or embarrassing. Or it can mean that patient and psychoanalyst are stuck; the patient is returning again and again to some desire or grievance that the psychoanalyst is failing to tackle. A boring person might be feeling envious, and might kill a conversation – disrupting it or paralysing it – because he cannot bear to hear a helpful or compelling idea coming from someone else. Or the boring patient may be playing possum – just as there are beasts in the jungle that survive by playing dead, some people, when frightened, simply shut down. It’s also true that psychoanalyst and patient will sometimes unconsciously collude to desiccate the atmosphere between them because they fear things becoming too emotionally disturbed, or too exciting.

Some psychologists object to the word “happiness” because it can mean anything from a temporary pleasure to an almost mythical sense of eudaimonic purpose that few in reality manage to reach. So in lieu of happiness, more nuanced terms like “well-being,” “wellness,” “thriving,” and “flourishing” have become common in the popular psychological literature. We use those terms in this book. Marc is particularly fond of the terms thriving and flourishing because they refer to an active and constant state of becoming, rather than just a mood. But we still use “happiness” at times for the simple reason that this is how people talk about their lives. Nobody says, “How’s your human flourishing?” We say, “Are you happy?” And it’s how, in casual conversation, we both find ourselves talking about our research as well.

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.