Each year, a group of happiness experts from around the globe rank 156 countries based on how "happy" citizens are, and they publish their findings in the World Happiness Report.
Happiness might seem like an elusive concept to quantify, but there is a science to it.
When researchers talk about "happiness," they're referring to "satisfaction with the way one's life is going," Jeff Sachs, co-creator of the World Happiness Report and a professor at Columbia University, tells CNBC Make It.
"It's not primarily a measure of whether one laughed or smiled yesterday, but how one feels about the course of one's life," he says.
Since the report began in 2012, Nordic countries — which include Denmark, Norway, Sweden, Finland and Iceland, plus the Faroe Islands, Greenland and Aland — consistently turn up at the top of the list. (The United States, on the other hand, typically lands somewhere around 18th or 19th place.)
In 2019, Finland was ranked No. 1 for the second year in a row. In 2017, it was Norway, and Denmark grabbed first place in 2013 and 2016. Switzerland nabbed the top rank in 2015.
This is no coincidence. Nordic countries rank so high on the happiness report because they have things like free education and healthcare, low crime rates, cushy social security nets, a relatively homogeneous population and they're fairly prosperous.
Perhaps most importantly, these countries prioritize balance, which is the "formula for happiness," Sachs says. "They're not societies that are aiming for all of the effort and time to becoming gazillionaires, they're looking for a good balance of life and the results are extremely positive," he says.
"We find happiness in our own pursuits," like our professional work and passions, he adds. "And by living in societies that are more balanced."
Here's how the Nordic countries find work-life balance.
"What the science shows is that the one thing that will make us happy is having a little bit more time," Laurie Santos, a professor of psychology at Yale who teaches The Science of Well-Being, tells CNBC Make It.
A "full-time" workweek in Denmark is typically 37 hours spread over the course of five days. On the other hand, the average American works 44 hours per week, or 8.8 hours per day, according to the Bureau of Labor Statistics.
But what's even more striking is the Danes' attitude toward working long hours. While many Americans see working late as badge of honor and a way to get ahead, in Denmark it's seen as a weakness — it shows you can't get things done in the allotted work time, Kay Xander Mellish, a Danish business consultant and author of "How to Work In Denmark," tells CNBC Make It. Most employees leave work around 4 p.m., according to the Ministry of Foreign Affairs of Denmark.
"There is a sense that, yes, work's important and you need to get your work done to a high quality, but you also need to make sure it's balanced appropriately," Alex Calvert, an expat who has lived in Copenhagen for seven years with his wife and two kids, tells CNBC Make It.
To be as efficient as possible, Danes don't really socialize at work, or take breaks to run errands, Mellish says. "You might be there only 7.5 hours but you're working that whole time," she says. Free time is "the most important thing they have," so it's rare that people would hang out with coworkers after working hours, she adds.
Flexible work arrangements are also common. For example, Saara Alhopuro, who works as a diplomat in Helsinki, Finland, tells CNBC Make It that she only goes into a physical office three times a week. She's allowed to work remotely one day a week, and then spends the rest of her free time working on her hobby: photographing mushrooms.
In Denmark, full-time employees are guaranteed five weeks of vacation time, regardless of their position or field of work.
To put that in perspective, the average American worker with five years of experience is given 15 days of paid vacation, according to the Bureau of Labor Statistics. However the United States doesn't provide a federal paid vacation policy. According to a 2019 study, 23% of Americans don't receive paid vacation and 22% don't get paid holidays. On top of that, only 41% of U.S. workers feel like the organization they work for encourages employees to take time off, according to the American Psychological Association. Surveys have shown that more than 55% of Americans aren't using all their paid time off.
That's not the case in Denmark, according to Mellish. "People take every single hour of their time off," she says. If you try to contact someone in Denmark and Sweden in late July or August, they'll very likely be away "enjoying their vacation time," Sachs says.
In Finland, many people spend their summers in cottages, called "mokki," where they unplug and relax with family and friends.
Contrary to popular belief, "giving ourselves some free time can improve our productivity rather than decrease it," Santos says.
Christina Konig Koehrsen, an art student from outside of Copenhagen, tells CNBC Make It that she left her job in advertising for eight months because she was stressed, and the work simply wasn't making her happy.
"[I]t didn't let me have that work-life balance that we cherish so much here," she says. "And so, we have a system that made it possible for me to quit my job and have some thinking time and figure out what's my next step in life." During that time, Konig Koehrsen got $2,000 a month from the Danish government.
People typically go on "stress leave" when things are so bad at work that it's affecting their mental health, Mellish says. Stress can be "a career-killer, to be honest," she adds, comparing it to a "low-level disability."
This safety net between jobs is part of Denmark's "flexicurity" labor market model, which allows businesses to be flexible, and people to get security from the government.
Under this model, it's very easy for employers to fire and hire people. On the flip side, employees can pay fees ($62.54 a month on average) to an unemployment insurance fund and get up to two years of pay if they lose their job and meet certain requirements (like minimum earning and residency requirements), according to the Ministry of Foreign Affairs. The government also provides education and counseling to get people back to work.
Konig Koehrsen, for example, is now going to school to become a painter and receives an educational stipend of $1,000 a month from the government.
Freedom is another value that matters in a society, and determines someone's well-being, Sachs says. "Can you shape your life the way you want? If you're trapped by poverty, if you're trapped by debt, the answer will be no," he says. "If you have an opportunity to pursue the kind of life you want, the answer is yes. And if yes, that makes people a lot happier."
No matter where you live, research shows that finding work that really maps onto your core values can make you happier, Santos says. "Finding your signature strengths and working with them rather than against, that's one big thing you can do," she says.
Although the culture and safety net in Nordic countries seems to promote happiness, life is not all warm and "hygge."
"We pay for this every single day, and we do it in more than one way," Mellich says. Nordic countries pay some of the highest taxes in the world. In Denmark, for example, there's a 25% sales tax, and a 150% tax on cars.
People in Nordic countries are happy to pay those taxes because they get great universal social services in return, Anu Partanen, author of "The Nordic Theory of Everything," tells CNBC Make It. For example, daycare, public education including college and healthcare. "All of those are included in your taxes," she says.
Living in the happiest country in the world also puts pressure on people to be happy, Konig Koehrsen says. "It might be that expectation to have a work-life balance here that stresses people out, that you both have to work, but you also have to take care of your family," she says.
Don't miss: The 5 best cards for shopping at Costco
Like this story? Subscribe to CNBC Make It on YouTube!