Most people hope to live long, healthy and happy lives, but few are able to travel the world in an attempt to unravel the formula for longevity. That's exactly what Dan Buettner did. Since the early 1980s, Buettner has teamed up with National Geographic and scoured the globe for places where people live much longer than average. This is how the concept of 'Blue Zones' was born. Following on from his bestseller, Dan travels the world to research the diets and lifestyles of the people who live the longest.