What makes us happy and fulfilled? What is the key to longevity and health? How do you balance family, work and friendships? You could spend a lifetime trying to decode these elusive, fundamental questions of existence, and still be left wanting.

Turns out, a group of researchers at Harvard Medical School have put in the hard yards for you. Conducted over the course of 75 years, the Harvard Grant Study was one of the longest, most comprehensive studies in history, following the lives of 268 Harvard undergraduates from the classes of 1938-40.

The candidates were assessed every two years on their mental and physical health, career enjoyment, retirement experience and marital quality, providing unrivalled insights into the human experience and the impacts of life's trials and tribulations on well-being.

Read on to discover the top findings from this unprecedented study. 


Meaningful connection is everything

Every school of thought has their own magic silver bullet to happiness. The new-age mindfulness warriors profess that happiness is an 'inside job', the cult of celebrity puts fame and money on a pedestal and the academics preach service to others and lofty achievements.

According to the Grant Study, close, meaningful relationships trump all else in the pursuit of happiness and longevity.

George Vaillant, the study's director and Harvard psychiatrist explained, "Let me lay out 75 years of evidence that our relationships with other people matter, and matter more than anything else in the world."

"When the study began, nobody cared about empathy or attachment," said Vaillant. "But the key to healthy aging is relationships, relationships, relationships. Joy is connection (...) The more areas in your life you can make connection, the better."


Loneliness kills

The study also found an irrefutable link between the quality of our relationships and our mental and physical health, finding that close ties protect people from life's discontents, help to delay mental and physical decline, and are better predictors of long and happy lives than social class, IQ, or even genes.

The study found people who had happy marriages in their 80s reported that their moods didn't suffer even on the days when they had more physical pain. Those who had unhappy marriages felt both more emotional and physical pain.

Those who kept warm relationships lived longer and happier lives, said psychiatrist and director of the study Robert Waldinger, and those without a partner often died earlier. "Loneliness kills," he said. "It's as powerful as smoking or alcoholism."


You can create a happy ending, despite earlier misfortunes

The research also debunked the idea that people's personalities "set like plaster" by age 30 and cannot be changed.

A man named Godfrey Minot Camille went into the Grant study with fairly bleak prospects for life satisfaction: He had the lowest rating for future stability of all the subjects and he had previously attempted suicide. But at the end of his life, he was one of the happiest. Why? As Vaillant explains, "He spent his life searching for love."

"Those who were clearly train wrecks when they were in their 20s or 25s turned out to be wonderful octogenarians," he said. "On the other hand, alcoholism and major depression could take people who started life as stars and leave them at the end of their lives as train wrecks."


Money and status are not everything

The Grant Study's findings echoed those of other studies -- that acquiring more money and power doesn't correlate to greater happiness. That's not to say money or traditional career success doesn't matter. But they're small parts of a much larger picture -- and while they may loom large for us in the moment, they diminish in importance when viewed in the context of a full life.

"We found that contentment in the late 70s was not even suggestively associated with parental social class or even the man's own income," says Vaillant. "In terms of achievement, the only thing that matters is that you be content at your work."

So there you have it, money can't buy happiness. 

Happy wife, happy life: study reveals the key to lasting happiness