Walks in the park, stopping to smell the flowers, leaf-peeping — there’s plenty of age-old wisdom that says nature improves happiness.

But just how much of positive impact nature has on our health is only now being uncovered. The journalist and explorer Dan Buettner travelled the globe gathering the secrets of the world’s oldest, longest-living people. He found one thing that they all have in common: gardens.

Life in the blue zone

Buettner visited so-called “blue zones,” parts of the world where residents are known for their longevity: Okinawa in Japan, Nicoya in Costa Rica, Icaria in Greece, and Loma Linda in California and Sardinia in Italy.

While these far-flung locales do share familiar factors in healthy populations — plant-based diets, social support networks, and constant physical activity — Buettner found these locations also shared one unexpected characteristic, people who garden well into old-age.

“In Okinawa, they say that anybody who grows old healthfully needs an ikigai, or reason for living. Gardening gives you that something to get up for every day,” Dr Bradley Willcox of the University of Hawaii told the BBC.

Start digging

There’s another added benefit to that green thumb.

According to WebMD, pulling weeds and planting flowers could burn up to 400 calories an hour. So for those of you who don’t know the difference between a spade and a shovel, learning how to garden might be the perfect way to slim down and get healthier. Forget the gym — just hit the garden.