Sanjay Gupta talks with Dan Buettner author of The Blue Zone: Lessons for Living Longer From the People Who’ve Lived the Longest. A blue zone is a place around the globe with a disproportionately long living population, and Buettner goes to these places to study what makes them different. His three rules: 1. eat a mostly plant based diet 2. Regular low-intensity exercise 3. Invest in Family and Friends