In the case of architects, neither premise is true. One architect whose “advance obit” I wrote more than 10 years ago initially called me the “grim writer” but switched to calling my efforts “the kiss of life” after another productive decade. Indeed, most of the subjects of my advance research are still going strong. There are plenty of exceptions—as the recent death of Zaha Hadid reminded us—but many architects are busy as octogenarians and nonagenarians. And (though no statistics bear this out) that calling may keep them alive longer than members of other professions. So far this year, Harry Cobb hit 90, and his onetime partner I.M. Pei has reached 99.

In their book Twenty Over Eighty, magazine editor Aileen Kwun and graphic designer Bryn Smith have wisely bucked the trend of a youth-obsessed culture through stimulating interviews with the elders of the architecture and design worlds. For all their subjects, “work is not a burden but a necessity,” they write. But that doesn’t mean that these golden-agers are unburdened by frustration. One subject, Michael Graves, died last year, but not before lamenting that he had never had a real professional triumph—nothing, he said, like his friend Richard Meier, who “got the Getty Center in Los Angeles.”

Stanley Tigerman says, “Ethics loom very large for me—larger than design. I realize this makes me a dinosaur.” Tigerman remembers the days when “you couldn’t displace another architect before you wrote him a letter saying that this client, who was originally his client, approached you; you ask if he was paid in full, and so on.” Now, he complains, architects undercut other architects. But Tigerman is far from saintly. He calls his mentor Paul Rudolph “a bitch” and says he keeps his distance from the other members of the so-called Chicago Seven because “very few of them are really good architects.”

One of the surprises is finding Ricardo Scofidio, who in person barely looks 60, in the book. (He is 81.) In middle age, Scofidio says, he seriously considered leaving the profession. But, after meeting Elizabeth Diller, he realized he “didn’t have to practice architecture the way the profession practiced it” but could choose multidisciplinary projects that were “like jumping off a tall building without a parachute.” Scofidio was already well into his 60s when their temporary Blur Building (2002) in Switzerland created a sensation.

Disappointingly, the subjects don’t talk much about the trials of old age. An exception is Denise Scott Brown, who describes managing husband Robert Venturi’s caregivers. “I’ve become the HR person for this little group,” she says (though she does not discuss his infirmities). On a typical day, she adds, “Bob goes off to the office and does nothing, and I stay here and work.”

The interviewers ask nearly every one of their 20 subjects (such as graphic designer Milton Glaser, the late product designer Richard Sapper, and planning and design professionals Jane Thompson and Beverly Willis), “What advice would you give your younger self?” Graves said he might have moved his office from New Jersey to Manhattan, to get bigger jobs. Phyllis Lambert says, essentially, follow your passion. But, she adds “You can’t just be passionate; you have to be really hard-hearted, too.” Scott Brown offers this bit of wisdom: “Architects think of themselves as the captain of the ship, steering. I think you’re better off thinking of yourself as a surfer, catching the wave.” And with the right wave, she might have added, you could get a very long ride.