100-year-olds have interesting advice on how to live longer, but 'you cannot use it as guidance,' expert says

The number of centenarians, or those who live until 100, is on the rise, prompting many of us to wonder: What's their secret? 

To find out, it makes sense to go straight to the source and ask these super-agers what they are doing differently. 

Experts, however, advise caution. 

Petr Sramek is the CEO of Healthy Longevity Clinic, a medical practice that uses health biomarkers, such as blood pressure or DNA, to create a plan that will lengthen a client's life. For a hefty price tag, the clinic will design you a "roadmap" based on your own health needs. 

Even though Sramek is in the business of selling longevity, he recognizes that, at this point, many of those who live until 100 years old simply have the right biomarkers. 

Advice from this demographic might be interesting, but "you cannot use it as guidance for anyone else," he says. 

Those who have reached 100-years-old are likely benefitting from a confluence of factors, including so-called longevity genes. These genes are "not super common," Sramek says. 

"Probably up to 2% of the population has these factors," he says. "These people do not need to follow the best lifestyle. They can drink or not exercise or maybe smoke. They are still living longer and are in good health, but they are the exceptions. You cannot use anything from their lifestyle as an example." 

A person might credit their longevity to rigorous, regular exercise, he says. But if you have specific heart or bone conditions, this might not work for you.

Many centenarians also credit their longevity to having a positive attitude. This will likely not add years to your life, says David Watson, a professor of personality psychology at the University of Notre Dame.

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"The effects of just being positive are overstated," he says. In fact, the personality trait that is most associated with a longer life is conscientiousness, or being careful and diligent.

"If you talk to people who have lived to be 100, they will give you interesting insights but also an unusual sample," Watson says. 

The formula for a long life, experts agree, is likely not held by anyone who has lived one.

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