We all want to live a good life — no one looked back from their deathbed and was ever comforted by a feeling of “Meh.” But what it means to live well (not to mention how to achieve it) is murky. If asked, most of us would talk about doing more — studying harder, running farther, eating better, giving more (and of course, all of it mindfully) — as if a good life is the result of mere accumulation. And maybe, in the end, it is — but accumulation of what, precisely, other than years?

What it means to thrive

“Since the end of the 20th century, there has been a quest in science to better understand human fulfilment and thriving. There’s been a shift towards wanting to understand how humans can function as highly as possible,” said Dan Brown, PhD, a sport and exercise scientist at the University of Portsmouth. “Part of the reason for a lack of consensus is the research so far has been narrowly focused. Some have studied what makes babies thrive, others have examined what makes some employees thrive and others not, and so on.”

Brown, with co-author Rachel Arnold, an expert in the psychology of performance excellence, set out to change that, to give people a blueprint for how to thrive. To do so, he compiled and reviewed all the research on what makes people thrive — from studies of babies and teenagers, to studies of artists, sportspeople, employees and the elderly — to create the first definitive catch-all, published in the journal European Psychologist.

They found that what it takes to thrive, rather than merely survive, could be as simple as feeling good about life, about yourself and being good at something.

“It appears to come down to an individual experiencing a sense of development, of getting better at something, and succeeding at mastering something,” Brown explained. “In the simplest terms, what underpins it is feeling good about life and yourself and being good at something.”

Brown’s study led him to outline the traits and circumstances upon which he built his simple definition of thriving. The secret to how to thrive isn’t having all of the components, he said, but rather cultivating a combination of some from each of the two columns below:

Yet thriving, according to Brown’s definition, feels like half the story. From social competence to social support, living well, it seems, is highly dependent on our interactions with others. Which wouldn’t shock the researchers involved in the longest study of human happiness.

The (open) secret of happiness

In 1938, 268 sophomores at (then-all male) Harvard University volunteered to take part in a study of human health that would follow them for the next 80 years, meticulously examine every aspect of their lives, and go on to follow the lives of their children in what is now known as the still-running Harvard Study of Adult Development. Some became alcoholics, some struggled with mental illness, others lived typical lives of varying degrees of professional and personal success and happiness, and still others were some of the highest achieving men of their generation — US president John F. Kennedy, for example, was one of the original participants.

Over the eight decades that followed, researchers tracked the ups and downs of the men’s health, careers and relationships, to arrive at a startling conclusion: More than money or professional success or fame, more than social class, IQ or genes, it’s our close relationships that determine how happy we are.

“When we gathered together everything we knew about them about at age 50, it wasn’t their middle-age cholesterol levels that predicted how they were going to grow old,” said the study’s current director, Dr. Robert Waldinger, a professor of psychiatry at Harvard Medical School, in a 2015 TED Talk about the study’s findings. “It was how satisfied they were in their relationships. The people who were the most satisfied in their relationships at age 50 were the healthiest at age 80.”

Interestingly, this was as true for the original participants (who, one can assume as Harvard students, were highly privileged) as it was for 456 men from Boston’s poorest neighborhoods, whose lives had been tracked in a separate study since the 1930s (the two lines of research were combined in the 1970s under the same umbrella of the Harvard Study of Adult Development). It also appears to be true for women, too, though they’ve only been included in the study for little more than a decade.

“Those good relationships don’t have to be smooth all the time,” Dr. Waldinger said to the New York Times in 2016. “Some of our octogenarian couples could bicker day in and day out. But as long as they felt that they could really count on the other when the going got tough, those arguments didn’t take a toll on their memories.”

This isn’t to say that marriage, or partnership, is essential to a good life. While other research has consistently found long-term, committed relationships to have a positive effect on well-being across the board, “over and over in these 75 years,” Dr. Waldinger said in the 2016 article, “our study has shown that the people who fared the best were the people who leaned into relationships with family, with friends and with community.”

In which case, living a good life, a thriving, happy life, isn’t about doing everything more,  but about doing something we’re good at, with people we love — and, perhaps, extending the same to them.

“Kindness,” Gertrude Weaver told TIME, when asked her secret to a long and happy life a year before she died at age 116. “Treat people right and be nice to other people the way you want them to be nice to you.”