I researched longevity after my grandmother lived to 104. Here are 6 things that might help you become a centenarian.

A man whose grandmother lived to 104 studies longevity. He said having a positive mindset and getting married might help you become a centenarian.

• William J. Kole's grandmother lived to 104, and he became fascinated by longevity.
• He's written about a woman who lived to be 122 — the oldest documented person ever. 
• Kole says society will need to change to accommodate a booming number of centenarians.

This as-told-to essay is based on a conversation with William J. Kole, author of "The Big 100: The New World of Super-Aging." It has been edited for length and clarity.

My grandmother's life spanned three centuries. She was born in 1899 and died in 2003, just before her 104th birthday. She told stories about the changes she witnessed that would make me go weak in the knees. For example, one of her first jobs was playing piano for silent movies, and yet she died in the age of home screening and 3D films.

My grandmother sparked my fascination with extreme longevity. My curiosity was deepened when I worked for The Associated Press in Paris. There, I reported on Jeanne Calment, who lived to 122 years and 164 days — the longest documented life span in history. Just before her 121st birthday, Calment released a rap album. The title translated to "Time's Mistress."

My mother is 93 and still living alone in the house I grew up in, but my dad died at 67, and my brother died at 59. I'm 63, which means I could be just past middle age by family standards or have one foot in the grave. That's part of the reason I set out to learn everything I could about people who live to be 100 or older — and how our society will change as more and more people reach triple digits. Here's what I discovered.

A positive mindset goes a long way

We often think of exercise and a healthy diet as the only proven ways to boost longevity, so I was surprised to learn that mindset plays a massive role. A study from Yale found that people with a positive mindset about the aging process lived about 7 ½ years longer than people with less positive perceptions of aging. We tend to think of the body and mind as separate, but they're not.

Faith will help you live longer, too

Another piece of research that surprised me was that people who practice a religious faith live about four years longer than people who don't. It doesn't matter which religion you observe: Researchers believe the social aspect of attending religious services helps increase life span. In fact, they found that nonreligious people who volunteer and who have rich social networks live almost as long as people who consider themselves religious.

Marriage might be a pain, but it will increase your life span

Any comic knows the frustrations of marriage are good for a few laughs. While any long-term relationship has ups and downs, having a partner might help you live longer. One study found that among men between 65 and 85 years old, those who were married lived two years longer on average than unmarried men.

Stress is an absolute killer

The effect of chronic stress on your life span surprised me as well. Research shows that toxic stress can impact every cell in your body and accelerate the aging process. After learning that, I was inspired to leave my job in the 24/7 news cycle and pursue writing books — a much more relaxed pace of work.

Longevity isn't equitable

The impact of chronic stress might help explain one of the more concerning findings: the racial disparities in longevity. Black Americans, on average, die six years earlier than their white counterparts. That's a lot of life they're missing out on. There's so much we must do to address this, including lifting people out of poverty. After all, being in a higher socioeconomic bracket is also associated with a longer lifespan.

Our society is going to shift as we get older

The number of people living to 100 and older is projected to grow eightfold by 2050. Half of today's 5-year-olds will live to be 100. That brings up a number of questions about education, ageism, and economics: How will we earn enough to pay a century's worth of bills?

My biggest concern is how the climate crisis will affect our lives as we get older. No one wants to live to over 100 years old on a planet that's more and more unstable. That's the scary part of my research, but it's important. On the bright side, we're going to have bonus years — maybe decades — to create and to love. That could be a beautiful thing.