What, then, have researchers in positive psychology discovered as the factors that promote true well-being? Some have recognized that, to understand human nature as a set of universally shared attributes, we must examine the human psyche from the standpoint of evolution. Ninety-five percent of human history was spent in bands of nomadic hunter-gatherers, and our basic needs, desires and emotions evolved to make our ancestors successful in that milieu. We prize sweet and fatty foods, for example, because they were hard to find in the savanna, and when our ancestors came across them, it was a good idea to gorge on them.

Although our modern world makes a separation between work and pleasure, one of our deeply evolved needs is to do work that is meaningful and challenging. An important aspect of well-being revolves around being engaged purposively in work, setting goals for ourselves and then striving to achieve them. Interestingly, researchers have discovered that it’s the journey, not the destination, that gives us the greatest pleasure. Once we’ve accomplished a goal, there’s a short-lived pleasurable sensation, and then before we know it, we’ve set ourselves a new goal.

For our hunter-gatherer ancestors, being accepted as part of a community was essential for survival. Because of this, we have evolved fundamental needs for multiple layers of connection with others, from the broadest to the most intimate, including a sense of community belonging, friendship, family bonds, physical intimacy and partner love. Raising children, interestingly, has been shown to increase eudaimonic, but not hedonic well-being: parents report feeling more stressed on a daily basis but enjoy greater long-term life satisfaction. The same pattern of increased eudaimonic but reduced hedonic well-being has been reported in volunteer work. Having a positive attitude to life is one of the most important attributes for sustained well-being. Just as we saw a self-reinforcing upward spiral between positive emotions and physical health, the same kind of dynamic exists in the relationship between attitude and long-term happiness. People who believe their happiness can improve report greater life satisfaction. The same is true for those who emphasize gratitude, both to others and for the positive aspects of their own life. Another emotion demonstrated to elicit both greater happiness and health is awe: the sensation of being in the presence of something vast, something greater than our own limited existence.

In fact, simply being in nature is one of the most reliably effective ways to feel happier and healthier. A classic study in 1984 reported that surgical patients assigned to rooms with windows looking out on a natural scene took fewer painkillers and had shorter post-operative hospital stays. Since then a number of studies have shown that nature-assisted therapy is effective across a wide range of diagnoses, from obesity to schizophrenia. Of course, you don’t need to be sick to benefit from the natural world. According to a recent study, spending at least two hours a week in nature gives people an overall sense of greater well-being.

Perhaps the most important attribute of all – one that both incorporates and transcends many of the rest – is having a sense of meaning and purpose in life. This relates directly to Aristotle’s core idea underlying eudaimonia – striving to fulfill the plenitude of one’s true nature. Viktor Frankl, a Nazi concentration camp survivor who wrote about his experience in the classic Man’s Search for Meaning, observed that the common attribute of those who survived the horrors of the camps was ‘the will to meaning’. Someone who ‘knows the “why” for his existence’, Frankl wrote, ‘will be able to bear almost any “how”.

After reading this inventory of lasting happiness, you may identify some attributes you already have, and others you wish you could have but don’t. A reasonable question to ask is whether there’s anything you can do about it. Can we really cultivate our own shoots, as Mencius suggested, to achieve eudaimonia as an integrated organism?

For much of the twentieth century, the consensus scientific view was that Mencius was wrong – there is a ‘happiness set point’ that is genetically determined, and there’s very little we can do to change it through self-cultivation. Some studies reported that people who enjoyed extreme good fortune, such as winning the lottery, found themselves no happier several years later; and by the same token, those who endured tragedies, such as getting paralyzed from an accident, eventually returned to their prior level of life satisfaction. While there does seem to be a happiness baseline that varies for different people, this deterministic view has been largely repudiated. It’s been shown, for example, that significant life events such as marriage can lead to a sustained increase in life satisfaction, and conversely that serious ill-health reduces it.

Most importantly, the discovery of neural plasticity in recent decades has opened up a vast arena of possibilities for intentionally changing one’s own happiness baseline, rather than relying on the serendipity of life events. If we engage in practices that redirect our neural attractors, they have the potential to durably alter the baseline of our inner experience. Mencius’s primary teaching – that we can intentionally cultivate ourselves just as we might nurture a plant – has been corroborated by modern neuroscience.