As a social worker for older adults, Robyn Golden, 67, preached the importance of staying active as you age. In her early career, Golden was often inspired by the way her clients tackled new challenges.

“I found it very enriching,” she said, to see that “they can change, and they can grow.”

As she has gotten older, she has tried to embrace that openness to new experiences. But she didn’t realize how hard it could be for an older person. Last year, for example, she took up pickleball. She wasn’t expecting to play professionally, but she assumed she would improve alongside the younger students in the class she joined.

When she didn’t, she started to think about quitting. “I’m in this class and all these people are progressing and I’m not,” she said.

A conversation with a friend changed her mind. “I realized, they’re all thirty-some years younger,” she said. “I hadn’t even thought of that.” Golden, now associate vice president of social work and community health at Chicago’s Rush University, stuck out the class, and she still plays every week.

That is an experience echoed by other social workers, professors and researchers who study aging in America. Many have spent decades working with seniors, but they found that getting older themselves shifted their thinking and what they tell their clients.

Some are surprised by how much fun they are having. Others have had to adjust their expectations of themselves and their bodies. And all acknowledge that some of the biggest obstacles facing seniors include the rising cost of health care, the dearth of affordable housing, and the astronomical fees for nursing homes or assisted living.

We spoke with more than a dozen experts to gather their thoughts on aging, and what they would tell their younger selves. Here are some of the most common lessons:

Find a project you care about — even after retirement

Katharine Esty, 90, has never been afraid of new challenges. The psychologist earned her PhD in her 50s and retired just three years ago in Concord, Massachusetts.

Even so, she feared slowing down. “We’re sold a bill of goods about loss and decline” as an expected part of aging, Esty said. “I started to believe it myself.” To combat her dread, Esty interviewed 120 octogenarians about their lives. What brought them joy, even as they lost partners and suffered physical setbacks?

Her conclusion: People with a project or a passion they were pursuing were in much better mental and physical shape.

“They were climbing huge mountains, doing things they’d never done before,” she said. One book-loving friend had always wanted to try teaching. After retirement, he worked up the courage to lead English classes at an institute for retirement learning. He’s still at it years later.

Research has shown that learning cognitively demanding skills as we age, such as quilting or digital photography, can improve memory, brain health and well-being. Older adults engaged in activities they enjoy live longer, happier lives and develop fewer diseases, according to the National Institutes for Health.

Esty’s conversations — which eventually became the book “Eightysomethings: A Practical Guide to Letting Go, Aging Well, and Finding Unexpected Happiness” — made her realize that she needed to rethink her assumptions about her own old age. Though she had pictured a restful retirement, she realized she would be happier pursuing creative projects and speaking engagements — and it would probably be better for her mental and physical health.

“I enjoyed work and had lots of energy,” she said. “It completely revolutionized what I expected in my old age.”

Leanna Clark-Shirley, 44, president and CEO of the American Society on Aging, said she hears often from older adults who say they have shed their inhibitions as they have aged, diving into a new hobby or business.

“In every conversation I have with someone in their seventies or eighties, the fear or hesitancy has gone away,” she said. “Rather than viewing aging as a time where you lose things, [they see] aging as something that can happen concurrently with new interests and new adventures.”

Focus on adaptability, not just resilience

Bruce Leff, 63, has built his medical career around treating — and studying — aging. So it’s not surprising that he gets asked one question over and over: What’s the best way to grow old?

When he was younger, the Baltimore-based doctor had a set of standard health recommendations for older people: exercise and eat well, though no need to avoid the occasional glass of wine or dessert.

But as he has eased into senior citizenship, Leff saw greater nuance. “As you get older, you understand different aspects of life,” Leff said. “You’ve had your own experiences, you’re more empathetic.”

Resilience, Leff said, is a popular term among doctors, who urge their patients to stay tough through discomfort or unpleasantness until things return to normal. Now he’s come to see adaptation — adjusting and accepting what life throws your way — as equally important.

Many of his patients are struggling with life-changing events, such as the death of a spouse, a cancer diagnosis or even retirement. Though many go through a period of “feeling a bit lost,” he said, “the vast, vast, vast majority of people find their way to seeking happiness and purpose and meaning.”

Ellen Langer, a 78-year-old Harvard University psychology professor, who studies the connection between mind and body, says that viewing aging positively — and focusing on what you are able to do, not what you can’t — can improve your health and mental state.

Much of the research she does has focused on how to stay happy through old age. In one well-known experiment, eight septuagenarians were briefly moved into a facility that had been meticulously styled to resemble the world as the subjects knew it 20 years ago. They were all encouraged to live as if they were their younger selves. After the experiment ended, Langer found that many of the subjects had improved vision and overall health.

As Langer has gotten older, she hasn’t suffered the same discontents as many of her peers because she said she avoids the negative thinking about aging that traps other people. “I don’t walk around experiencing my age,” she said. “Age is not a relevant dimension to me.”

Don’t get discouraged — and don’t be too hard on yourself

Michael Schuchert, a 54-year-old personal trainer who primarily works with older clients at DeHenzel Training Systems in Northern Virginia and D.C., always knew the importance of being fit, but he only became interested in training after a running injury pushed him into physical therapy.

Schuchert realized that he needed to adjust his routine to his changing body. His clients, who range in age from their 40s to 80s, do as well. Some are interested in building upper-body strength so that they can pick up their grandchildren. Another wanted to improve her balance after a bicycle accident caused some neurological issues. One recent milestone: She was able to put on her pants while balancing on one leg.

“As I’ve aged, I’ve started to feel more aches and pains,” Schuchert said. He finds his body is a little more delicate now, and it takes longer to recovery from injuries. “I need that core [muscle] … because I still have 25, 30-plus years ahead of me.”

Golden said that as a younger social worker, she didn’t always see the appeal of shared senior living, with its exercise classes and group activities. But now she finds the idea of a comfortable living space much more attractive.

This taught her to focus closely on the interests of her patients, even if she didn’t connect to their desires. “We can’t put people in boxes,” she said. “I think that’s what I’ve learned.” She’s trying to do the same for herself, even as she continues to think about new hobbies, such as mastering a musical instrument, and traveling more.

“I always assumed I have to learn to play cards,” at some point, she said, because that’s what the older people she knew did. And while researchers have also found that playing cards or other games regularly can improve brain health, Golden now realizes it may not be for her. “Maybe I’ll try it,” she said. “But maybe not.”