"To me, when I work, I'm happy," said Martinez, who's not sure he ever wants to retire.
Though research has shown people across age groups are more likely to report job satisfaction than dissatisfaction, older workers consistently have expressed more happiness with their work than younger people have.
The AP-NORC survey found significant minorities of people reporting unwelcome comments at work about their age, being passed over for raises and promotions, and other negative incidents related to being older. But it was far more common to note the positive impact of their age.
Six in 10 said colleagues turned to them for advice more often and more than 4 in 10 said they felt they were receiving more respect at work.
Older workers generally have already climbed the career ladder, increased their salaries and reached positions where they have greater security, so more satisfaction makes sense, says Tom Smith, director of the General Social Survey, one of the most comprehensive polls of American attitudes.
(Read more: LinkedIn's elderendorsers: Boomers driving growth)
"It increases with age," said Smith, whose biannual survey is conducted by NORC at the University of Chicago. "The older you are, the more of all these job-related benefits you're going to have."
Looking at the 40-year history of the GSS, the share of people saying they are very or moderately satisfied with their jobs rises steadily with each ascending age group, from just above 80 percent for those under 30 to about 92 percent for those 65 and older.
But as in the AP-NORC survey, the age gap grows among those who derive the greatest satisfaction from their work, as 38 percent of young adults express deep satisfaction compared with 63 percent age 65 and up.
Smith says earlier in life, people are uncertain what career path they want to take and may be stuck in jobs they despise. Though some older workers stay on the job out of economic necessity, many others keep working because they can't imagine quitting and genuinely like their jobs.
Eileen Sievert of Minneapolis can relate.
The French literature professor at the University of Minnesota used to think she would be retired by 65. But she's 70 now and grown to love her work so much, it became hard to imagine leaving. She's instead just scaled back her hours through a phased-retirement program.
"I just like the job," she said. "And you don't want to leave, but you don't want to stay too long."
(Read more: Six feet under as a retirement plan?)
Walter Whitmore, 58, of Silver Springs, Ark., feels the same. He says he has plenty of things to occupy him outside of his account representative job at a grocery distributor, but having a reason to get out of the house each day brings a certain level of fulfillment. He sees working as keeping him vibrant.
"It wasn't a goal to live to do nothing. You live to accomplish things," he said. "You have to maintain that functionality or you turn into Jell-O."
Robert Schuffler, 96, still reports for work most days at the fish market he opened in Chicago decades ago. He has turned over ownership to a longtime employee, but he can't imagine not seeing the customers he has known so long, and who still show up with a warm smile, a kiss for Shuffler and a shopping list. His job does more than just keep him feeling young: It keeps him happy.
"It's like some guy would make a million dollars today," he said. "He's very happy with the day. I'm very happy being here."
—By The Associated Press