At 73, George Cavedon could be spending his days on a golf course in Florida with friends who have long been retired. But the New Hampshire resident would rather mentor younger coworkers and chat up clients than measure putts on a green.
Cavedon tried out retirement in his fifties and quickly discovered it wasn’t for him. The flexibility was nice, but he was soon bored with spending his days puttering around the house, and missed the camaraderie of a workplace. He likes to ski and golf, but could only spend so much time on those two hobbies. Plus, his wife and kids had their own routines, often leaving him alone. So he decided to pursue a second career, this time in marketing at a small firm. He’s been there for 18 years, and has no intention of taking his foot off the gas anytime soon.
“Retirement to me is a scary thing. How much can you lay on the beach?” Cavedon tells Fortune. “For my own personal mental health and well-being, I like being active and working.”
Cavedon is part of a growing number of baby boomers, many of whom are college-educated, who continue to work well past 65 not because they can’t afford to retire, but simply because they love their work—and don’t want to give it up.
Read more: More Americans are working past age 65—and that’s good news for employers
In fact, the number of those who have continued to work past 65 has quadrupled since the 1980s, according to the Pew Research Center. Now, almost 20% of Americans 65 and older are employed, nearly double the share of those who were working 35 years ago. In total, there are around 11 million Americans 65 or older who are working today, accounting for 7% of all wages and salaries paid by U.S. employers. In 1987, they made up 2%.
And, as Pew’s research also shows, for many of those older Americans, they work not just for the money, but, like Cavedon, for the camaraderie as well as the mental stimulation.
“I go on my vacations, I do what I want to do,” he says. “I get up in the morning, and I have a place to go, that’s what I like. I like going to work.”
A much higher portion of baby boomers have college degrees compared with generations before them, and have worked less physically taxing jobs. This first generation of knowledge workers is contributing to “a huge, exponential shift” in America’s economy, says Mark Walton, a journalist and the author of Unretired: How Highly Effective People Live Happily Ever After, which tells the story of Americans ages 60 to 80 who have opted out of leaving the workforce. The title refers to the accelerating trend in baby boomers retiring and then returning to the workforce.
“They are transforming professional and executive career trajectories and what they may look like for generations to come,” Walton tells Fortune.
In his book, Walton highlights the experiences of Americans over 60 who are still working high-stress jobs, including entrepreneurs and doctors at the renowned Mayo Clinic. Over and over, these workers told him they tried to retire, but were bored or began to feel as if they lacked purpose (a well-documented issue in retirement). Loneliness, an American epidemic, is even more common among retirees.
The anecdotes are backed up by research. Early on, Walton cites a study from two psychologists that looked at the experiences of 1,500 retirees and 400 people of the same age who were still working. The study found that only around 44% of the retirees were happy with their lives. The others, more than half of those surveyed, reported feeling some combination of loneliness, emptiness, and hopelessness.
“The more successful you’ve been, especially financially, the more likely you are to feel like a failure in retirement,” says Walton. “What kind of a person doesn’t want to have money and be retired? Turns out there’s a certain kind of person. They’ve been in careers, they’re very curious and very competitive.”
As the U.S. grapples with what the future of work will look like, this group of baby boomers is claiming its stake, Walton says, and in the process reshaping workplaces and societal expectations.
Changing perceptions
At first blush, working longer might not seem like such a positive change. There is a pervasive fear among younger generations in the U.S. that they may never retire at all—not because they’re so passionate about their work, but because they won’t be able to afford it.
Their fear isn’t completely unfounded. Gen X and younger will have different financial outcomes than baby boomers, thanks to the decrease in pensions and a larger reliance on personal savings for retirement that started with Gen X and kicked into high gear with millennials and Gen Z. Articles and studies abound about the lack of savings and retirement preparedness in the U.S. Long-held perceptions of work also are changing among younger generations: While college-educated boomers may find much of their identity and purpose at their nine-to-five, that mindset is shifting.
Walton acknowledges that America’s retirement crisis is “serious and sad.” There is a significant portion of the population who can’t afford to retire, and poverty among elderly Americans has been on the rise. But there is also a growing contingent who refuses to retire, even well past the age many workers have typically been considered less productive or valuable.
Read more: Fellow Gen Xers: That retirement crisis you’re losing sleep over is a ‘rewirement’ opportunity
To Walton, the latter trend is a refreshing change. Boomers are flipping the script on an ageist work culture that might have forced them out in the past—and still does, in many cases—while more companies are recognizing they can provide invaluable experience and expertise, and can mentor younger workers. That is empowering, he says, not cause for alarm.
It also, to Walton, seems like an inevitable trend. Humans are living longer than ever, and many more have enjoyed long careers in offices compared with the physically taxing work more common in the factories of previous generations. Though working longer doesn’t appeal to everyone, it may be necessary in some cases.
“The reality is, there is a labor shortage, and the labor shortage is a shortage of highly skilled, highly knowledgeable employees,” says Walton, noting that a baby bust followed the baby boom, leading to fewer younger workers to take over many jobs. “It could always be predicted that the time would come when companies would have to find experienced professionals and couldn’t find them among younger people. There simply isn’t enough of them.”
‘I’ve got decades ahead of me’
A hard-stop retirement—there today, gone tomorrow—can be especially difficult for retirees to manage. Work takes up a significant portion of many people’s lives, and after 40-plus years, making the abrupt switch to completely unstructured days without the built-in social interaction was hard on many of the people Walton interviewed for his book.
More companies are creating other options for older workers. So-called phased retirement allows workers to gradually reduce their hours, go part-time, or switch to contractor status, among other arrangements. Workers maintain an income and get to keep doing the work they love, but more on their own terms.
That’s the hope of Renee Stanton, 61, who has worked in IT-adjacent roles her entire career. While Stanton could afford to retire, she enjoys what she does and has no desire to leave the workforce completely. She just wants some flexibility to go skiing and sailing—her lifelong passions—during the on-seasons, and to spend more time with her adult children and aging parents.
Read more: Count me among the boomers shunning retirement. I’m leading a startup in my 60s despite being set for life
Stanton says while retirement sounds nice, she learned a lesson from her father, a cabinetmaker who retired in his early sixties. Still going strong—and still retired—at 87, his one regret is leaving the workforce too soon, she says.
Her plan is to eventually move to a contractor role. That way, she can work throughout the shoulder seasons on her own terms, and then take time off when she’s skiing or sailing, or work remotely from the mountain cabin she rents in the winter. She has decades of experience to offer, she says. She just wants to “control the spigot” of when and where she works.
In an ideal world, she’ll be able to ski or “catch waves” in the morning and work a little in the afternoons, giving her that “intensity and enrichment” she also craves.
“I’ve got decades ahead of me, knock on wood,” Stanton says. “I’m funding my ski addiction now.”
What is your retirement budget? Fortune is writing about what Americans at different income levels are spending in retirement. To share your story, email senior writer Alicia Adamczyk at alicia.adamczyk@fortune.com.