Across the world, there are communities where residents live longer, healthier and more independent lives than anywhere else on the planet. People here suffer lower rates of killer diseases and enjoy many more years of good health in old age than the average. Up to ten years more. And these places also produce more centenarians.

Aged 74, broadcaster Jon Snow, has finally stepped away from the news desk and into the world of semi-retirement. He travels to the Greek island of Ikaria, where a culture of organic food, wine, left-wing politics, partying and modest incomes has cultivated the ultimate stress-free and life-extending island life.

In California he finds a community of 7th Day Adventists who are living longer by a very different approach. Following strict religious doctrine, they believe their bodies are temples to God – literally. Theirs is a life of abstinence: no alcohol, meat, cheese – even coffee. Over 80s hit the gym daily at 6.30am – except on the Saturday Sabbath, which is reserved for spending with family and disconnecting from technology.

In Japan’s Nagano prefecture, Jon learns how a state-wide public health intervention carried out by an army of volunteers transformed life expectancy. He visits a village where people work hard in the fields until 80, meets a family where four generations live under one roof and great grandparents keep young by looking after toddlers.