One of my friends, more so than anyone else I know, has a remarkable power to make the people around him happy. He does this not through beer or flattery, but simply through the power of his personality. He is extroverted, conscientious, agreeable–all the traits that psychologists predict will attract a lot of friends.

But there's one personality characteristic of his that I find especially winning: his enthusiasm. He is excited about his work and fascinated by mine. He speaks ebulliently about his family but also about the economy and politics. He has, as the 19th-century philosopher William James put it, "zest [for] the common objects of life."

My friend is also an unusually happy person, which I had always thought explained his enthusiasm. But I had it backwards. In truth, enthusiasm is one of the personality traits that appear to drive happiness the most. In fact, to get happier, each of us can increase our own zest for the common objects of our lives. And it isn't all that hard to do.

Research on personality goes back millennia, to ancient Greece at least. In the fourth century B.C., Hippocrates theorized that our characters are made up of four temperaments: choleric, melancholic, sanguine, and phlegmatic. These, he posited, were due to a predominance of one of the four humors, or fluids, in one's body: yellow bile, black bile, blood, and phlegm.

Although medical knowledge has overtaken this approach–for example, black bile doesn't even exist–Hippocrates foreshadowed a good deal of our modern thinking on personality. During the 20th century, scholars developed a personality typology that we still use today. In 1921, Carl Jung distinguished between introverts and extroverts; in 1949, the psychologist Donald Fiske expanded on that work when he identified five major personality factors. Later research further refined the features of these traits and named them openness, conscientiousness, extroversion, agreeableness, and neuroticism.

Over the past 70 years, the Big Five have been used to investigate and explain many social phenomena. For example, as I have written, extroverts tend to make friends easily, but introverts tend to form deeper bonds. When people high in neuroticism who have money make more money, many of them enjoy it less than those lower in neuroticism. People who are more extroverted and conscientious tend toward conservatism, whereas those who are more open to new experiences typically espouse more liberal views.

Two traits out of the Big Five seem to be especially important for happiness: In 2018, psychologists confirmed that high extroversion and low neuroticism seemed to be the recipe for well-being. More specifically, the correlations hinged on one aspect of extroversion and one aspect of neuroticism–enthusiasm and withdrawal, respectively.

You might say that enthusiasm and withdrawal form the poles of a spectrum of behavior. Enthusiasm is defined as being friendly and sociable–"leaning into" life. Withdrawal denotes being easily discouraged and overwhelmed, leading one to "lean out" of social situations and into oneself. If we could become more enthusiastic and withdraw less, the data suggest, we would become happier. We might become more successful too. "Nothing great was ever achieved without enthusiasm," Ralph Waldo Emerson wrote in his 1841 essay "Circles." "The way of life is wonderful: It is by abandonment."

Perhaps we could conceive of the perfect personality for achieving the happiest life. Of course, this is only helpful if you can change yours to better fit that ideal. This is unlikely, given that huge personality changes are generally only associated with a traumatic brain injury. However, as my colleague Olga Khazan has written, smaller shifts are possible. In one 2020 study, scientists asked people to record their ordinary activities, reminding them by text message to act in certain ways, such as being a bit more conscientious or open than they ordinarily would. It worked: Their behavior changed, at least as long as they were studied.

If you want to lean into life more enthusiastically, you might try something similar by setting up a system of reminders. For example, you might schedule an alarm on your phone or an email to yourself each day that says, "Open up to all the people and things you see today!" But there are other, deeper interventions worth trying as well.

1. Use the "as if principle."

In his magisterial 1890 text, The Principles of Psychology, James (a Harvard professor and an Atlantic contributor) outlined a radical philosophy of behavior change: Fake it. "We cannot control our emotions," he noted. "But gradually our will can lead us to the same results by a very simple method: we need only in cold blood act as if the thing in question were real, and keep acting as if it were real, and it will infallibly end by growing into such a connection with our life that it will become real."

As the psychologist Richard Wiseman argues in his book The As If Principle, James's approach is surprisingly effective. Academic research undertaken by the psychologists Seth Margolis and Sonja Lyubomirsky bears this out, showing that if people act more extroverted in general, they do in fact succeed and become happier.

Faking enthusiasm is fairly straightforward. When you want to withdraw from social activities (perhaps you are overwhelmed or bored), act as if you were enthusiastic instead. Tell yourself, "I am going to get into this right now." This will, the research suggests, establish new cognitive habits that gradually become more automatic.

Obviously, you can push this too far. I am not suggesting that you muster enthusiasm for something dangerous or use it to escape your problems. ("Today, I will enthusiastically act as if I didn't have to pay my taxes!") Instead, use the principle to nudge yourself toward positive changes.

2. Reframe challenges as chances.

One of the most popular self-improvement writers of the 20th century was the Protestant pastor Norman Vincent Peale, who sold millions of books on positive thinking. One of his titles was Enthusiasm Makes the Difference, in which he shares advice from a sage friend: "Always be glad when there is trouble on the earth … for it means there is movement in heaven; and this indicates great things are about to happen."

It's easy to dismiss this thinking as Pollyannaish and unscientific, but it is a good example of reframing a problem as an opportunity. This is a common strategy in creativity and innovation, and a successful technique in business leadership. Entrepreneurs routinely use reframing after setbacks by asking questions such as "What did I learn from this?" You can increase your enthusiasm for things you would ordinarily withdraw from by affirming, "This is hard for me, which is why I am doing it," or something similar.

3. Curate your friends.

One of the best ways to become more enthusiastic is to hang around enthusiastic people such as my friend. (I'm not giving out his number; you have to find your own.) By doing this, you'll be taking advantage of what psychologists call "emotional contagion," in which people adopt the emotions and attitudes of those around them. If you tend to withdraw, it may be easy to gravitate toward people who do the same. But consciously doing the opposite can help you borrow a better personality trait from those around you. Look for companions who lean into life with gusto. Although it might seem like a chore at first, you'll be more likely to "catch" this spirit and become enthusiastic about the friendships.

Fighting your tendency for withdrawal doesn't mean that you can never be alone. There is a difference between a neurotic withdrawal from life and deliberate solitude. And the inability to be without company and stimulation is not necessarily a mark of good health either. What matters is your motive: whether you are moving away from others or toward being alone (or, conversely, whether you are moving toward others or away from your own thoughts).

Henry David Thoreau didn't write Walden as an exercise in withdrawal but rather as an enthusiastic endorsement of finding oneself in the company of one's thoughts. His description of waking up alone in a cabin by Walden Pond is a portrait of enthusiasm. "Every morning was a cheerful invitation to make my life of equal simplicity, and I may say innocence, with Nature herself."

Even if your surroundings aren't as picturesque as Walden, you can choose to treat every morning, every interaction, and every setback as a cheerful invitation. You can make your head into your own cozy cabin, and make life inside it a little brighter.