We've already told you about Blue Zones, where people just tend to live longer than they do anywhere else. That's important to keep in mind since predicting lifespan is an inexact science — there are a lot of factors that can affect it, including genes, diet, hobbies, and location. In a new study published in International Psychogeriatrics, researchers traveled to a place that isn't officially a Blue Zone but is certainly a strong contender. One out of every 10 residents of Cilento, Italy is over 100 years old. By contrast, centenarians only made up 0.02 percent of the population of the United States in 2010. There's clearly something special about Cilento, and the researchers paid it a visit to discover what set the most aged of the elderly there apart from their younger neighbors.

The study focused on the psychological states of 29 people between the ages of 90 and 101, and 51 of their relatives between the ages of 51 and 75. Incidentally, these participants were selected as part of a larger look at the area's aging process called the Cilento on Aging Outcomes (CIAO) Study. The researchers evaluated each of those participants on their physical and mental health using self-assessment, doctors' opinions, and the views of their friends and family. When they compared the older generation to the younger one, they found some fascinating data.

One thing that surprised the researchers was that there wasn't a big connection between physical wellness and mental wellness in later life. While the 51- to 75-year-olds scored better on their physical health, the 90-somethings and centenarians scored better on self-confidence, decisionmaking, and mental well-being. The mental strengths most strongly expressed by the 90+ set boiled down to a few positive thought patterns.

For Cilento residents, longer life was strongly correlated with life-affirming mental states. Resilience (the belief that you can withstand the obstacles that get in your way) was chief among them, with optimism (the belief that things will generally go well) right behind it. Good relationships were important as well, which has also been strongly correlated with overall happiness — in Cilento, that was generally expressed via family, community, and religious connections. One factor that seemed unique to this particular region was a love of the land, which could be seen as an offshoot of the positive community relationships. But the factor that stood out the most has also been observed among long-lived people around the world: willingness to work.

"There is no need to ever retire, but if one must, it should be a lot later than 65," said then-97-year-old Shigeaki Hinohara in 2009. The physician and educator died in 2016 at the age of 105, but he was true to his word — he continued to work 18-hour days up until a few months before his death. Even far away from Blue Zones, staying in the workforce has been linked with a longer life. In the United States, just waiting until age 66 to retire instead of 65 was enough to decrease the likelihood of death by as much as 11 percent. There you go: If you want to live longer, maybe you should plan on retiring a little after the usual schedule.

Get stories like this one in your inbox or your headphones: sign up for our daily email and subscribe to the Curiosity Daily podcast.

For more ways to boost your life expectancy, check out "The Blue Zones: 9 Lessons for Living Longer From the People Who've Lived the Longest" by Dan Buettner. We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.