Why is it that some people can live past the age of 100, while others suffer poor health and die decades earlier?

The centenarians of Pakistan’s Kashmir district say the key is a tough lifestyle, like the one they live in the mountains. Japanese 103-year-old, Hidekichi Miyazaki, ascribes his good health to competitive sprinting and spoonfuls of his daughter’s tangerine jam, while Maritime centenarian Nellie Harris told CTV Atlantic her secret was a happy childhood, a low-fat diet and low stress. “Worry kills a lot of people,” she said.

Many assume genetics must explain long life, but scientists studying centenarians haven't yet found many common genetic links between them.

Certainly, lifestyle plays a big role. A healthy diet low in sugar and high in vegetables, beans, and whole grains is a big factor. So are avoiding smoking and heavy drinking .

But what about all the other factors? Why are there groups of seniors in places such as Okinawa, Japan and Ikaria, Greece regularly living past the century mark? Here’s a look at what researchers are learning about the keys to longer, healthy lives.

1. Daily movement is key

Daily movement is key

You had to know that exercise was going to figure prominently on a list of ways to live longer. That’s because it’s pretty clear by now that getting our heart rates up several times a week is crucial to good health.

But exercise doesn’t have to mean weights and treadmills; in fact, many nonagenarians and centenarians have never seen the inside of a gym. What these seniors do know about, though, is hard work.

National Geographic researcher and author Dan Buettner set out in 2000 to find the lifestyle secrets to those pockets of the world where people live the longest -- areas he calls Blue Zones. He says it doesn’t matter whether it’s in an Adventist community in the U.S., or an old world community in Sardinia: seniors who live the longest engage in lots of daily, physical work. Not exercise, just everyday movement.

That work includes tending to vegetable gardens, chopping firewood, kneading bread by hand and of course, walking everywhere.

Canadian physician and researcher Dr. Mike Evans suggests many of us could benefit by adding more moments of exercise to our daily routine, simply by adopting small behaviour changes, like taking the stairs instead of escalators -- anything  to “make your day harder."

2. Find challenging work

Find challenging work

University of California psychologist Howard S. Friedman performed one of the longest studies on longevity, picking up the research of another psychologist, Lewis Terman, who started studying 1,500 kids in 1921 to see who lived longest and why. The result of those decades of research was a book Friedman co-wrote with colleague Leslie Martin called "The Longevity Project."

The team came to several interesting and perhaps counterintuitive conclusions about aging -- including the finding that hard, sometimes stressful work is actually good for your health. The authors say it’s assumed that all stress is harmful, but they found that people who are ambitious and work hard throughout their lives thrive in every way, including by living longer.

Friedman’s team found it didn’t matter whether someone worked at their dream job or had dull, menial work: those who found meaning in aiming for and accomplishing goals, and who stayed motivated by setting higher goals, were the ones who were most likely to live a long life.

3. Stay connected to friends

Stay connected to friends

Several studies in recent years have shown that living alone, feeling lonely, and being socially isolated alone all increase the risk for premature death. In fact, loneliness could be just as dangerous to our health as smoking or being obese -- perhaps even more so.

One study that analyzed data from several other studies on loneliness found that people who were socially isolated, lonely or living alone had about a 30 per cent higher chance of dying during the study periods (which averaged about seven years), compared to those who had regular social contact. The effect was greater for younger people than for those over 65.

The authors say having close friends and family seems to offer a protective effect on health, perhaps because our social connections offer us motivation to take care of ourselves and avoid risky behaviours. Whatever the reason, it seems that stronger social ties lead to better emotional and physical health.

4. Get a good education

Get a good education

Even when accounting for all the emotional, lifestyle and genetic reasons for why some people live longer than others, statistics show one factor always stands out: education level.

It doesn’t matter a person’s gender or race or even what part of the world they live in, the more education that a group of people has, the longer they can expect to live.

Researchers at the National Center for Health Statistics at the U.S. CDC say that educated people simply tend to have healthier behaviours and are more likely to avoid unhealthy ones. They also tend to have more access to medical care when they need it -- all of which leads to better health and longer life.

5. Have a sense of purpose

Have a sense of purpose

After speaking with seniors on the island of Okinawa, Japan, National Geographic’s Buettner found many talked about their “ikigai” -- their reason for living and for getting up in the morning.

Whether it was taking care of their grandchildren, tending to a garden, or working on a hobby, many of the Okinawans told him that having responsibilities and feeling needed helped them live well into their tenth decade of life.

A recent study in The Lancet also found that having a sense of purpose can increase lifespan. The study of 9,000 seniors found that those who felt the highest sense of control and believed their lives were worthwhile were 30 per cent less likely to die during the 8-year study period. On average, those with the highest well-being lived two years longer than those with a lower sense of wellbeing.

A Canadian study of 6,000 participants made similar findings, with the study author noting that feeling one has a sense of purpose is particularly crucial to older adults, as many lose that feeling after they retire from the workforce.

Here are more of Buettner’s tips for living past 100: