What does ambition look like at 90? How do you explain the drive that makes people like Giorgio Armani, fully in command of his global design empire as he approaches his 10th decade, tick? When artist Betye Saar wakes every day, she sets to work on creating the assemblages that are widely exhibited and avidly sought by collectors and major museums — artwork with origins she traces to her girlhood in the Watts neighborhood of Los Angeles, during the presidency of Franklin D. Roosevelt.

Why bother? Wasn’t retirement supposed to be the goal of a contented old age? The old, as it happens, represent a rapidly growing global population: The proportion of those 65 and above is increasing at a faster rate than those below that age, according to World Population Prospects, a United Nations study. Between 2022, when the report was issued, and 2050, the global population of those over 65 is expected to rise to 16% from 10%.

People are already working longer, and as they do, it would appear that a road map is needed as a means of understanding what keeps people like Martha Stewart not only undiminished by age but actively in the game.

Over the past months, we asked what makes people like Armani, Saar and Stewart so seemingly unstoppable.

The Unstoppables is a series about people whose ambition is undimmed by time. All interviews have been edited and condensed.

Martha Stewart, 82

‘Never-ending curiosity’ (and a few regrets)

This year I made time to grow the best vegetables, monster vegetables, that I’ve ever grown in my life. My houses are never done. And I’m writing my autobiography. That’s the scariest project for me because I don’t really like everything about myself — where I’ve been, what I’ve done.

I get up at 6:30 every morning. My housekeeper comes at 7, and I can’t be in bed when she arrives. That would be very embarrassing. I’m a bad sleeper, in any case. At times I’d rather watch a documentary. Other times, I might be anxious, not for me but for my grandchildren. If I wake in the night, I read the headlines to make sure we’re not being bombed.

Maybe a little uncertainty can help fuel ambition. When I left my job on Wall Street, I knew I had to create a career for myself. I became a caterer, catering parties every night. Still I thought, “Will there come a time when my granddaughter — she’s 12 — is asked, ‘What did Grandma do?’ And all she can say is, ‘Oh, she made parties for people.’” I thought, “I have to do something more than this.” That was in the 1980s, when I wrote my first book, the one on entertaining.

At that time I wasn’t keeping my eye on the home, even though I was known as a homemaker. It wasn’t enough for a marriage. Maybe I regret not having had more children. Maybe I regret that my marriage ended abruptly. We’d been together 27 years. That used to be considered a long time, so when a long marriage ended, it was like somebody died. Maybe I would have liked getting married again. I didn’t, but I don’t mind. Still, I’m curious about what could have been.

My never-ending curiosity drives me. Will it stop? That’s never even occurred to me.

Current and upcoming projects: Autobiography in progress; an untitled Martha Stewart documentary from R.J. Cutler, who directed “The September Issue,” to stream on Netflix in 2024; a PBS documentary series, “Hope In the Water,” set for broadcast in 2024; a partnership with Samsung for a 2023-24 advertising campaign; a line of gardening clothes and accessories in collaboration with French Dressing Jeans and Marquee Brands.

— Ruth La Ferla

Betye Saar, 97

Making some of the best work of her life

Being raised during the Depression, we all learned to be creative with what we had on hand. At Christmas or on my birthday, I always got art supplies, and I was jealous that my siblings got bikes and stuff. I realize now that my parents were fostering my creativity.

An early influence on my becoming an artist was Simon Rodia. My grandmother lived in Watts, and we would walk by the Watts Towers when they were being built. I was fascinated by how he used bottle caps and corn cobs and broken plates — trash, essentially — to make art, to make something beautiful. Then, much later, in the 1960s, I saw the work of Joseph Cornell. He refined the use of found objects and materials and boxes, and I thought, “Wow, I’ve kind of been doing that, too.” I didn’t know it was called assemblage, but it made sense to me and set me in that direction as an artist.

The main challenge, I guess, to being an artist is how to make a living. But being a creative person means you have to find ways to do this. I studied design at UCLA, and after I graduated, I made greeting cards; I made jewelry; I got into printmaking and then sold my prints. I taught art classes in colleges all over the states. My creativity kept evolving with my needs as I got married and bought a house, had my daughters and put them through college. Through it all, I loved making art. It kept me going.

I still want to make art. Sometimes in the morning when I wake up, it’s hard to get out of bed, hard to get back into my body and get it to move. But I do it. Not everyone has a reason to get out of bed, something they love to do and that gives their life meaning. I am so lucky that I have that as part of my life. I don’t really think about my age, unless someone mentions it, though I guess I feel middle-aged — which for me is, like, 50 to 70. It would be kind of neat to live to 100, to have 100 revolutions around the sun. I’m pretty close.

Current and upcoming projects: Completed “Drifting Toward Twilight,” an installation at the Huntington Library in San Marino, Calif.; “Betye Saar: Heart of a Wanderer” exhibition at the Isabella Stewart Gardner Museum in Boston; “Betye Saar: Serious Moonlight” at the Kunstmuseum in Lucerne, Switzerland; and completed a newly commissioned artwork for “Paraventi: Folding Screens from the 17th to the 21st Century” at the Fondazione Prada in Milan.

— Guy Trebay

Giorgio Armani, 89

He doesn’t think much about age

For those of us who grew up in the shadow of war, ambition was something natural, a vital drive. It was not so much a desire for fame and notoriety but rather an urge for personal fulfillment, a way to assert oneself outside the hardship and to overcome it. My mother and father taught me the value of commitment and hard work to get things done. It is a lesson that has never left me.

It took me some time to find my way. First, I studied medicine, then came La Rinascente (an Italian department store, where Armani worked in display) and Cerruti — fashion, in other words. That was the moment when I found my ambition, when I discovered the power of clothes not only to change the way you look but, more profoundly, to influence the way you are and behave.

I think the challenges — or problems — and the rewards of staying in the game go hand in hand if you do this work for as long as I have and if you remain present. The main pressure is staying relevant without giving in to the pressures of the moment, which often feel very urgent but are forgettable in the long run.

In truth, I don’t think about age much. In my head, I am the same age I was when I started Giorgio Armani. Situations and people change, but the challenges and problems are all the same in the end. My way of tackling them hasn’t changed — with great determination. Audiences evolve, however, and this cannot be underestimated. Stylistic coherence, therefore, must be elastic. Otherwise one becomes rigid. The ultimate gratification is to become a classic — outside of and above fashion — and to be identified with a style.

Current and upcoming projects: Designed 14 men’s, women’s and haute couture collections in 2023.

— Guy Trebay