Age is just a number, and this is clearly evident in the lives of the three centenarians interviewed in the LifeHunters video above.

Each has his or her own story — Clifford Crozier, born in 1915; Emilia Tereza Harper, born in 1913; and John Millington Denerley, born in 1914 — but you'll notice a certain "je ne sais quoi" that they all seem to share.

Positivity and strength are certainly apparent, along with a will to live and a continued interest in and curiosity about the world around them.

Even as times changed, these people kept on living, adapting to and welcoming the new phases of their lives. It's this fortitude and emotional resilience that has likely played a major role in their longevity.

Emotional Resilience and Optimism Help You Stay Young at Heart

Each of the centenarians in the video look far younger than their chronological years, and they certainly don't act their age (who knows how a 100-year-old is "supposed" to act anyway). Their positive attitudes undoubtedly are to credit for helping them stay young at heart, and research backs this up.

In a study of 100 seniors (average age of 81), those who were exposed to implicit positive messages (words like creative, spry and fit) experienced gains in their physical strength.1

It's evidence that your mind truly does have power over your body, and all of the centenarians interviewed exemplify this. If you believe your body and mind will fail you as you age, it may very well follow suit.

But the opposite also holds true, especially if your positive mindset is combined with the basic requirements for healthy living (like good sleep, fresh healthy food and staying active).

The majority of centenarians report feeling about 20 years younger than their chronological age, and their mindset has a lot to do with this self-perception.

Though Denerley is 102, for instance, he states that he feels like he's 69 or 79. There's a good chance, too, that if you were to evaluate his biological age, it would be closer to how he feels than to his actual chronological age.

Interestingly, experts also agree that using acceptable biomarkers to determine biological age (such as blood pressure, muscle power, skeletal mass and fitness indicators) would be a better indicator of lifespan than chronological age.2

Centenarians Eat Real Food

Notably, none of the centenarians were self-proclaimed health nuts, but they do understand the value of eating real food. There was no other option when they were born, after all. As Harper noted, she grew up eating home-cooked food. What else was there?

And more than that, her family grew their own food as well. Everything they ate was taken fresh from their garden, prepared and then put onto their plates.

In 2017, the notion of eating home-grown, home-cooked food has become more of a novelty than a norm for many people, but reverting back to this traditional way of eating is the best route for health and longevity.

The simple act of eating whole food is a theme common to centenarians (even if their diets aren't "perfect," like Crozier's apparent fondness for whiskey on occasion).

Emma Morano, who, at 116, is the oldest person in the world, similarly shared with news outlets one of her dietary secrets: three eggs (two of them raw) and raw minced meat daily.3

Aside from what to eat, many centenarians also mention the importance of variations of intermittent fasting, i.e., not overeating, eating only once a day or, in Morano's case, having only a light dinner.

In Okinawa, Japan, which has an unusually high concentration of people who live to 100 and beyond, hara hachi bu, or eating until you're only 80 percent full, is said to be an important factor in longevity.4

Strong Relationships, Fond Memories and Living in the Moment

Another common thread among the centenarian trio? Strong, positive relationships. Each spoke fondly of their marriages which, though their spouses had passed decades earlier, still offered them fond memories. Each also was able to look back on their life experiences and relationships with appreciation and gratitude.

This, too, is backed up by science, with research showing that the types of social relationships someone enjoys — or doesn't — can actually put them at risk for premature death. In fact, researchers found a 50 percent increased likelihood for survival for participants with stronger social relationships.5

Harper, in particular, explained that she was able to live happily because she had a lifetime of memories to fall back on. It's important to remember this — that experiences tend to make us happier than possessions.

The "newness" of possessions wears off, as does the joy they bring you, but experiences improve your sense of vitality and "being alive" both during the experience and when you reflect back on it.

In addition, most centenarians, regardless of their health status, tend to have positive attitudes, optimism and a zest for life. In the video, you'll notice the trio make mention of living in the moment, living for the day and having no regrets.

These are people who, despite having more than 100 years of "past," are living very much in the present, not dwelling on what they have lost but appreciating all the living they have done (and have yet to do).

Also noteworthy, none of them has plans to go anytime soon. Each speaks of feeling strong and expects to continue living each day to its fullest. They are active — physically, mentally and socially. This, too, will only help them to stay young and healthy.

Helping Others Will Come Back to You Hundreds-Fold

Harper also spoke of the importance of being kind and helping those around you. This is a life lesson worth learning, as doing good deeds helps others in need while providing a natural mood boost for you.

Volunteering, for instance, can lower your risk of depression and anxiety and even boost your psychological well-being.6,7 Not only does it keep you active and on your feet, but there's a definite social aspect as well, both of which contribute to happiness and longevity.

Volunteering to help others also gives you a sense of purpose and can even lead to a so-called "helper's high," which may occur because doing good releases feel-good hormones like oxytocin in your body while lowering levels of stress hormones like cortisol. Personality traits can also affect your longevity, which may also be playing a role in the centenarians interviewed.

Having a sense of purpose and staying productive, for instance, have been shown to promote longevity in The Longevity Project, a Stanford study spanning 80 years.8 Conscientiousness, specifically, was identified as a marker for longevity. The reason for this, the researchers believe, is because conscientious behavior influences other behaviors.

For example, conscientious people tend to make healthier choices, such as avoiding smoking and choosing work they enjoy and life partners they get along with — factors that can have a significant impact on their stress level and general contentment. Conscientious people also tend to be more productive, even past conventional retirement age, and tend to regard their work as having purpose.

The Longevity Project dismisses the idea that hard work will kill you early. On the contrary, those who stay productive and work hard all their lives actually tend to be happier, healthier and more social compared to those who don't work as hard. Co-author and psychologist Howard S. Friedman, Ph.D., of the University of California, said in an interview with the American Psychological Association (APA):9
" ... [O]ur studies suggest that it is a society with more conscientious and goal-oriented citizens, well-integrated into their communities, that is likely to be important to health and long life. These changes involve slow, step-by-step alterations that unfold across many years. But so does health. For example, connecting with and helping others is more important than obsessing over a rigorous exercise program."
Being a Lifelong Learner Is Linked to Longevity

It's interesting that Denerley mentioned if he had one regret it would be not taking his studies seriously enough early on. He recommended getting an education early in life as a crucial point, and this, too, is correlated with a longer life.

People with a bachelor's degree or higher tend to live about nine years longer than people who don't graduate from high school, according to a U.S. Centers for Disease Control and Prevention (CDC) National Center for Health Statistics report.10 This is likely, in part, because educated people may get better jobs, plan more for their future or lead healthier lifestyles. However, having a natural curiosity about life and a desire to keep learning likely also plays a role in the longevity connection.

There Is No Set Pattern for Why Some People Live to 100 and Beyond

Despite advances in science that have linked everything from eating more vegetables to the age your mother gave birth to you (younger being better) with a longer life, no one can lay out a set plan that will guarantee you'll live to 100. And the fact remains that centenarians and super centenarians (those who live to 110 and beyond) are a motley crew. According to Israeli physician Nir Barzilai of the Institute for Aging Research at Albert Einstein College of Medicine in New York:11
"There is no pattern. The usual recommendations for a healthy life — not smoking, not drinking, plenty of exercise, a well-balanced diet, keeping your weight down — they apply to us average people. But not to them. Centenarians are in a class of their own."
Based on years of data from studying centenarians, Barzilai reported that when analyzing the data from his particular pool of centenarians, at age 70:12
  • 37 percent were overweight
  • 8 percent were obese
  • 37 percent were smokers (for an average of 31 years)
  • 44 percent reported only moderate exercise
  • 20 percent never exercised at all
Despite this, Barzalai is quick to emphasize you should not disregard the importance of making healthy lifestyle choices, explaining:
"Today's changes in lifestyle do in fact contribute to whether someone dies at the age of 85 or before age 75. But in order to reach the age of 100, you need a special genetic make-up. These people age differently. Slower. They end up dying of the same diseases that we do — but 30 years later and usually quicker, without languishing for long periods."
'Keep Right on to the End of the Road'

What words of wisdom do centenarians have to offer to those with less life experience? "Time spent on reconnaissance is seldom wasted," Crozier said. "Be as independent as you can but don't be reluctant to ask for help when you think you need it." Harper has advice of her own, noting, "A good idea is to behave well to other people, show them respect and help them as much as you possibly can, and it will be repaid hundred-folds."

Denerley, too, has a motto for life, which he credited to Scottish comedian Sir Harry Lauder. It sums up, perhaps best of all, the attitude that's gotten him so far in life (especially when combined with his infectious smile), "Keep right on to the end of the road."