(CNN) People are living longer than ever before. Today, the majority worldwide can safely see themselves living into their sixties, according to the World Health Organization .

The country where people live longest -- measured as life expectancy at age 60 -- is Japan.

Coming a close second are a string of countries spanning the Mediterranean and East Asia, as well as countries with strong economies and healthcare systems.

By measuring life expectancy at age 60, factors such as childhood illness and issues earlier in life are discounted and longevity is more related to an individual's lifestyle and environment during older age.

We asked a selection of aging experts why these countries are outliving the rest -- and what secrets they hold to longer life.

Japanese values

Japanese people who make it to age 60 will live on to an average age of 86 -- longer than anywhere else in the world.

More than a quarter of the country's population are now over the age of 64 and the communities of Okinawa house the greatest proportion of centenarians of anywhere worldwide.

"Part of that is the traditional Japanese diet," says John Beard, director of Aging and Life-course at the World Health Organization (WHO). That diet includes plenty of fresh fish and vegetables, combined with low levels of meat and saturated fat. "But the traditional diet has changed," says Beard, speculating there is more to it than simply food.

"Another part of it is lifestyle ... and that they have systems which identify and treat key issues like blood pressure," says Beard. Active lifestyles into older years are the norm in Japan, helped by the country's extensive rural landscape getting people outdoors, and further aided by a well-established health infrastructure.

Sarah Harper, professor of Gerontology at the University of Oxford cites other reasons for Japanese longevity. "They tend to have a society which tends to promote a strong family set up and stress-relieving cultural activities," she says. Furthermore, Japan has less social inequality than many other countries, enabling everyone to experience these benefits.

A good diet, active lifestyle in the older years, stress relief and lots of support -- whilst we may know this is crucial, not all countries are adopting it.

Raise your glass to Southern Europe

"We have more older people in Europe than younger people already," says Harper. In the continent as a whole, more than half the population can expect to live into their mid-eighties, particularly in the south -- helped by their Mediterranean diet.

"Even if people take up a Mediterranean diet in older age, it can have health benefits," says Beard. The highly regarded diet traditionally consists of a small amount of wine, fresh vegetables, olive oil and, again, little meat and saturated fat.

Harper says the diet is better than ones rich in meat, fried foods and alcohol. "It's just a healthier option than what people in northern Europe tend to eat," he says.

A recent study found that people consistently consuming a Mediterranean diet were both physically and mentally healthier as they aged.

Italy, Spain and France have populations with an average life expectancy of 85 after passing the age of 60 and Beard thinks their cultures and warmer climates have a role to play.

"There's a culture of physical activity, and the climate is one that makes that relatively easy," says Beard. In countries with cold, harsh winters, maintaining an active lifestyle becomes a challenge.

Israel also has a life expectancy of 85 at age 60 and Glaser speculates this is most likely due to the diet. "So much morbidity at older age is due to heart disease," she says.

The social nature of these populations also comes into play. "Social relationships are important in these countries and family ties are strong," says Glaser. She believes that when people have a greater sense of belonging to a community, or family, and maintain a healthy work-life balance, their health improves.

"If one person engages in healthy behavior, others might also as well," says Glaser.

Thriving in old age with a thriving economy

In the other countries outliving the rest of the world, good health comes from wealth -- and the consequences of a strong economy and health system.

Singapore, Monaco, Andorra, Australia, Canada, Luxembourg, New Zealand and Switzerland are all on the list for a joint silver medal for life expectancy at 60 -- living to an average of 85.

"Places like Monaco have a huge wealthy immigrant population," says Harper, who believes immigration can also plays a role in the diet of a country's population and therefore its longevity. "Countries like Australia, Canada and New Zealand have large European populations that are probably eating similar kinds of diets," she says.

In general, countries with a smaller wealth and class divide have a healthier aging population.

"[In Singapore] there's a range of wealth and advantage; there are very few people at the bottom," says Beard. This uniformity means more members of the population can live the lifestyles needed to ensure good health -- well into their eighties.

And to top this all off, the outcome of a strong and equal economy is also a strong health system. "The health system in Australia starts to play a more significant role than in some other places as there is universal access to health services," says Beard.

If entire populations can access good health programs -- such as screening services -- chronic conditions that generally affect older populations can be picked up early and treated before they're irreparable.

But one thing helping us all live longer is that our lives today are easier than those of our ancestors.

"If you compare the lives of somebody in the 21st century to the life of somebody in the 19th century, we're not struggling on a day to day basis to survive," says Beard

"One of the things that's driving the aging of populations, is probably that we're generally living a less stressful life than our fore bearers."