With this in mind, researchers from several North American universities have analysed the lives of over 40,000 people in five countries.

Over a period of almost 30 years, they examined their level of general satisfaction, as well as their relationship to five essential dimensions of existence: health, income, housing, work and relationships.

It turns out that there is not just one, but a multitude of ways to be happy, specific to each individual and each context.

For some, happiness is based on tangible criteria such as income, employment or housing. For others, it depends on personal traits such as resilience or the search for meaning.

Some combine these two dimensions, while a minority seem to deviate from any pre-established model.

These findings call into question the two main theoretical models that have dominated until now. The first, termed “bottom-up”, assumes that happiness derives from satisfaction in the various areas of life.

The second, called “top-down”, argues that certain personal dispositions, such as optimism or emotional stability, influence one’s perception of happiness independently of external circumstances.

This study proposes a third, more flexible path, closer to reality, with a “bidirectional model,” in which internal and external factors are intertwined.

“These things are treated separately, but they aren’t really. They feed into each other at a personal level,” explained Emorie Beck, assistant professor of psychology at the University of California, Davis and first author on the paper, quoted in a news release.

To promote well-being, public policies should be designed to take account of this diversity, rather than rely on universal approaches.

“We have to understand the sources of happiness to build effective interventions,” said Beck.

In other words, raising a society’s level of happiness means taking each individual’s needs into account. The same policy can transform the lives of some, while making no difference to others.

This study has served as a reminder that there’s no magic formula for happiness. It is complex, specific to each individual, and sometimes even elusive.

But one thing seems certain: to better understand it, people need to stop thinking of happiness as a universal standard, and start thinking of it in terms of the individual.