Most people today fall prey to chronic diseases that strike in mid to late life — conditions such as cancer, heart disease, stroke and dementia — and end up nursing disabilities stemming from these illnesses for the remainder of their lives. Centenarians, on the other hand, appear to be remarkably resilient when it comes to shrugging off such ailments; they seem to draw on some reserve that allows them to bounce back from health problems and remain relatively hale until their final days.

Dozens of studies have investigated such individuals, with the goal of picking out the secrets to their salubrious seniority. Those analyses, however, have generally followed two separate if parallel tracks. The traditional approach has been to study the lifestyle and behavioral components of vigorous aging — the good habits, such as a healthy diet, regular physical activity and mental exercises that might keep the elderly vibrant through their golden years. The New England Centenarian Study, which includes 850 people entering their 100s, for example, has identified several behavioral and personality traits that seem to be critical to longevity, including not smoking, being extroverted and easygoing and staying lean.

Read more: How to Live 100 Years – Health Checkup: How to Live 100 Years – TIME.