The secret may have to do with what Japanese call ikigai . There is no direct English translation, but it's a term that embodies the idea of happiness in living. Essentially, ikigai is the reason why you get up in the morning. You may also like: <a href="http://www.bbc.com/capital/story/20160112-in-sweden-you-have-to-stop-work-to-chat">Can you work yourself to death? </a><a href="http://www.bbc.com/capital/story/20160112-in-sweden-you-have-to-stop-work-to-chat">Is this the secret to Swedish success? </a>' <a href="http://www.bbc.com/capital/story/20170413-we-had-to-give-them-bonuses-to-leave-early">We had to give them bonuses' to leave early </a> To those in the West who are more familiar with the concept of ikigai, it's often associated with a Venn diagram with four overlapping qualities: what you love, what you are good at, what the world needs, and what you can be paid for.

According to Hasegawa, the origin of the word ikigai goes back to the Heian period (794 to 1185). " Gai comes from the word kai ("shell" in Japanese) which were deemed highly valuable, and from there ikigai derived as a word that means value in living." There are other words that use kai: yarigai or hatarakigai which mean the value of doing and the value of working. Ikigai can be thought of as a comprehensive concept that incorporates such values in life. There are many books in Japan devoted to ikigai, but one in particular is considered definitive: Ikigai-ni-tsuite (About Ikigai), published in 1966.

Hasegawa points out that in English, the word life means both lifetime and everyday life. So, ikigai translated as life's purpose sounds very grand. "But in Japan we have jinsei, which means lifetime and seikatsu, which means everyday life," he says. The concept of ikigai aligns more to seikatsu and, through his research, Hasegawa discovered that Japanese people believe that the sum of small joys in everyday life results in more fulfilling life as a whole.

Japan has some of the longest-living citizens in the world -<a href="http://www.sankei.com/life/news/170301/lif1703010080-n1.html">87 years for women and 81 for men </a>, according to the country's Ministry of Health, Labor and Welfare. Could this concept of ikigai contribute to longevity? Author Dan Buettner believes it does. He's the author of Blue Zones: Lessons on Living Longer from the People Who've Lived the Longest, and has travelled the globe exploring long-lived communities around the world, which he calls " <a href="https://bluezones.com/books">blue zones </a>". One such zone is Okinawa, a remote island with a remarkably high number of centenarians. While <a href="http://news.bbc.co.uk/2/hi/uk_news/magazine/7250675.stm">a unique diet </a>likely has a lot to do with residents' longevity, Buettner says ikigai also plays a part.

"Older people are celebrated, they feel obligated to pass on their wisdom to younger generations," he says. This gives them a purpose in life outside of themselves, in service to their communities. According to Buettner, the concept of ikigai is not exclusive to Okinawans: "there might not be a word for it but in all four blue zones such as Sardinia and Nicoya Peninsula, the same concept exists among people living long lives." Buettner suggests making three lists: your values, things you like to do, and things you are good at. The cross section of the three lists is your ikigai.

For Japanese workers in big cities, a typical work day begins with a state called sushi-zum e, a term which likens commuters squeezed into a crowded train car to tightly packed grains of rice in sushi. The stress doesn't stop there.

Ikigai: A Japanese concept to improve work and life

Gaurav Dixit