Healthy Aging Image Gallery
Healthy Aging Image Gallery

Mamie Underhill celebrates her upcoming 105th birthday with her daughter, Leita Chapman, in Los Angeles, Calif., in 2002. See more healthy aging pictures.

David McNew/Getty Images

What does it take to live for 100 years or more? The question has intrigued both researchers and people from all walks of life for centuries: Greek myths touch on the question of eternal life, and a long line of researchers have studied this question, looking for patterns in the habits, genetics and health backgrounds of people who make it into a second century of life.

And those researchers are finding more subjects to study. The U.S. Census Bureau reported in 1990 that 37,306 centenarians -- people who have reached age 100 -- lived in the United States [source: Krach and Velkoff]. As of 2010, that number had boomed to roughly 72,000. The rise in centenarians is not just confined to the United States, either: Growth rates for this population in the United Kingdom show a similar boom [source: Sedensky].

But there's a difference between simply living to extreme old age and living a healthy lifestyle at age 100 or beyond. This is the key quest for many people interested in extending their lives as long as possible, and they take specific steps in the hopes that they'll be able to live healthy, active and vital lives in their advanced years.

Centenarians come from all backgrounds, ethnicities and walks of life. Although there are more of them in developed countries, likely due to better health care, some regions, known as blue zones, appear to have been producing centenarians since before modern medical advancements became available [source: Blue Zones]. One thing that connects many centenarians worldwide, however, is their approach to life and social interaction.

Centenarians are often described as being independent, outgoing and curious about the world around them. Neuroses, such as paranoia or the tendency to hold grudges, are rare in this group, regardless of nationality [source: New England Centenarian Study].

Healthy centenarians typically live on their own, or without the need for daily care from nursing staff or family. They also tend to be very active, whether in community or social groups. Centenarians commonly have many friends and spend a great deal of time with them. This group also shows a high degree of open-mindedness; they're willing to go with the flow when facing unexpected life events. And by and large, centenarians who have been interviewed about their longevity tend to express an overall sense of optimism. It appears that seeing the glass as half full is a helpful attitude if you want to see a triple-digit number on your birthday cake [source: Langreth].

Centenarians the world over have similarities that go beyond attitude and outlook. Next, we'll look at how diet and exercise appear to play a notable role.