Professor Ghilarducci added that today’s jobs might not require as much lifting, bending and stooping as the manufacturing or warehouse jobs of old, but a lot of jobs are plenty demanding, requiring keen eyesight and intense concentration. “People thought their jobs would get a little easier, but they’ve gotten a bit worse,” she said. “There’s a proletarianization of the jobs that older workers have.”

Helen Dennis, an author and consultant on retirement and an adjunct professor at the University of Southern California, says it is not surprising that a far larger percentage of Americans say they are going to work into their late 60s and 70s than actually do.

“A big factor is uncertainly,” she said. “People look at their savings and pensions and say, ‘I think it’s going to be O.K., but I don’t know. I don’t understand the Affordable Care Act, and my mother is 90 and I have a daughter who just got divorced who is coming to live with me. There are so many uncertainties that to be safe I’m going to work until whatever age.’ But then when people reach 61, 62, 63, a lot of them figure out that they can retire.”

Many Americans constantly weigh the pros and cons of continuing to work once they reach their late 50s and early 60s. Many conclude it’s not worth it. Ms. Dennis explained: “With the stresses of the workplace, with the mantra of doing more with less, now I’m doing two people’s jobs. We have a new manager. They’re changing the whole team again. The traffic here in L.A. is killing me, and my best friend just died and there’s a big message that life is short. I think that’s part of why people decide to retire.”

She added, “Some people realize that any job I can find is for a minimum wage, and it’s not worth my time.”

Ms. Dennis is pushing an idea called “Project Renewment” that seeks to help the nation’s first generation of career women plan for retirement. She says the hope is to make retirement more than “a return to the kitchen.” “The whole piece is how to help career women face their next 20 or 30 years — to find something you love to do and to give structure to the next chapter in one’s life,” she said.

Barbara Goldberg is a prime example of this approach. For 30 years, she conducted focus groups for Fortune 500 companies including IBM, Coca-Cola, American Airlines and General Motors. Ms. Goldberg, 72, held regular salons at her Los Angeles home for, in her words, “intellectual and socially aware women.” At one salon in 2008, a retired government official spoke about the problems facing drought-stricken countries in West Africa and the contaminated water that people drink there.