On a sunny morning, Ofer Leidner, a co-creator of an app called Happify, sat in a meeting room at the Fueled Collective, in SoHo, where about half of Happify’s staff works in a corner of a large, open-plan space, among some twenty other startup teams. The rest of Happify, the people who build the software, are based in Latvia. Leidner was wearing a black Henley, jeans, and black sneakers. Behind him was a wall of leather-bound books (wallpaper), and he sat in a handsome brown leather chair (real). “Happiness is an essential part of a healthy life style,” he said.

Until three years ago, Leidner had never heard of happiness science. “I was very skeptical,” he said. “I’m not a self-help person. I don’t buy these books.” Before he decided to go into the world-improvement business, by way of monitoring emotional fitness, Leidner ran a downloadable-games company. “Scientists actually have a very clear definition of happiness,” he explained. It’s a combination of two things: first, “positive emotions, how you feel about a given experience. We’re sitting down in a room. Are we enjoying it? Are we suffering?” And, second, “over-all life satisfaction.”

Happify, which launched last fall, serves about two hundred and twenty-five thousand “trainees”—people who sign up for a program of games and guided reflection that promises, on its Web site, “significant improvement in your level of happiness, with increases in positive emotions and life satisfaction.” The exercises—such as Shine On, in which you list three self-defined victories in your day, and Serenity Scene, which has you stare at a picture of a beach—are organized into twenty-six “scientifically validated tracks,” such as “Conquer Your Negative Thoughts,” “Get to Know Yourself Better,” and “Raise Happy, Resilient Teens.” Happify collects data on its users, and claims that eighty-six per cent of them get happier in two months. This is measured according to trainees’ responses to a series of happiness check-in questionnaires. (Leidner said they’re sharing the results with a psychologist at Northwestern, for further study.) Many happiness-seekers are recent college grads, stay-at-home moms—“the most unhappy group in America,” he sighed—and other “normal people who lead normal lives.” You don’t have to be clinically depressed to be glum. (After an initial assessment, I received a Happify happiness score of thirty-one out of a hundred, denoted by a diagonal-mouth unsure-face emoticon.) “There’s no shortage of topics by which people feel they’re not experiencing what happiness could be,” Leidner told me.

Happify got nearly four million dollars in early funding. Access to the basic system—ten happiness-boosting tracks—is free; you have to buy a membership, for fifteen dollars a month, to access the additional ones. Trainees spend, on average, twenty minutes per session, two or three times a week. A handful of psychologists and neuroscientists pitched in with feedback on how best to apply academic research, and they continue to vet ideas for exercises, or, as Leidner calls them, “interventions.”

For instance, Leidner said, humans have a built-in negativity bias. This was evolutionarily necessary, “so if you walked down Broadway, and a mammoth was there, you could run.” But all that negativity is a drag. Hence Uplift, a game that involves colorful hot-air balloons floating in a desert sky with different words attached. You must click on the balloons with cheerful labels to make them rise, and avoid the sad ones. Words from the positive balloons: “Hooray,” “Zest,” “Super,” “Puppy.” Words from the negative balloons: “Gloom,” “Perturb,” “Rash.” A plane flies by, with a banner trailing behind that reads, “Good.” Click on it for ten points. This goes on for three rounds. (“High score”: 930.)

“A huge part of it is self-awareness,” Leidner said. “There are countless benefits to mindfulness, which is, you know, all about savoring. When was the last time that you really thought about the water that you drink?” He pointed to a Mason jar on the windowsill. “Drink a cup of water, think about the taste of the water, and try to experience it with all of your senses.”

Leidner crossed the office floor, past a cozy communal sitting area with snacks, a popcorn machine, and two tall water dispensers, which had strawberries floating in them. “We are developing some new interventions,” he told me. His co-creator, Tomer Ben-Kiki, a middle-aged scuba-diving enthusiast, opened a Web page on one of his two computer screens. “In this example, the principle is that one of the ways to control your negative thoughts is by creating some interaction where you actually eliminate them or destroy them,” Ben-Kiki said.

Leidner cautioned, “This is a prototype.”

What appeared on the monitor was sort of like Angry Birds, but with small, purple, two-legged fur balls, which had been given various ornery labels. “Here you have these cute-slash-ugly creatures representing all the negative thoughts,” Ben-Kiki said. “So, let’s say I’m feeling ‘Shame’ today”—click—“and ‘Loneliness’ ”—click—“and ‘Anger’ ”—click. “You put those into this negative pedestal of yours.” He added them, one by one, to a collection at the bottom of his screen. He needed to choose five in order to advance to the slingshot phase. “Last one: ‘Hopeless.’ Yeah!”

“The game implementation is about smashing those negative thoughts,” Leidner said.

The purple monsters arrived in a new scene, awaiting slaughter.

The game had a ways to go. It has not yet been tried out on the company’s pool of some thirteen hundred testers, for whom the exercise must “affect the way they feel about their lives,” Leidner said.

Ben-Kiki added, “This is all shiny, but you would start with a background that’s gloomy and dark, so every time you eliminate one of them your scene lightens up a little bit. So you’re pushing the darkness out of your mind, in a sense—creating a visual metaphor for your mind.” (Five of five fur balls down. Sunny skies.)

Apparently, if you wonder whether monitoring your happiness might lead to some sense of anxiety or inadequacy about not being happy enough, you are fumbling the optimism for which Happify trains. (A “Cope Better with Stress” notification: “You have 1 day left to earn gold in part 1.”) “By no means do we want you to get obsessed,” Leidner said. “What happens is you develop these habits to become more aware, to become more grateful, to really focus about what drives you—and meaning.” Whatever that means. As long as you’re happy.

Illustration by Boyoun Kim.

CORRECTION: A previous version of this article misstated the number of tracks on Happify.