China’s population is aging rapidly. Three generations in a Beijing park.

During a scene in “The Sopranos,” the popular TV series on the Mafia, a reluctant gangster tells his mob boss Tony Soprano that he has inherited $2 million and he and his wife are thinking of retiring and moving south to Florida.

“What’re you, a hockey player?” Tony jokes. He reminds his friend that he took an oath and that retiring from their line of work is not an option. It turns out the gangster was also an informant for the F.B.I., and ends up killing himself in despair.

Fortunately, most of us have better retirement options. But the social security systems that many depend on to help them live comfortably later in life are facing the stark reality of an aging population, particularly in Japan and Western Europe, where the number of workers supporting retirees will drop precipitously in the coming decades.

Even China, the world’s budding superpower, is looking at some unfavorable numbers, an unintended consequence of its one-child-per-family policy.

China’s work force, which fueled its economic boom by providing cheap productive labor for its mines, factories and construction crews, has stopped growing, The Times reported. Demographers say it will begin to shrink within just five years while the population ages rapidly. By 2040, it is projected that the median age of Chinese will be higher than that of Americans, but Chinese will enjoy just one-third of the per capita income, adjusted for the cost of living, The Times wrote. Experts say that will make China the first major country to grow old before it is fully economically developed.

“There are tremendous demographic crises pending, unprecedented in Chinese demography,” Wang Feng, who heads the Tsinghua Center for Public Policy in Beijing, told The Times.

One of the solutions to the world’s retirement issues may be to think of the aging process in a new way. In his book “The Big Shift,” Marc Freedman believes that the period after midlife and before age takes its toll on our physical abilities - approximately 60 to 75 - is changing dramatically, The Times reported.

Mr. Freedman calls this part of life the “encore stage” and says this period is not about “clinging to our lost youth,” but applying talents that have been developed over a lifetime to a “purpose, contribution and commitment, particularly to the well-being of future generations,” according to The Times.

In the book, Mr. Freedman describes Gary Maxworthy, who after the death of his wife and decades in the food business joined Vista, a national service program designed to fight poverty in the United States. At a free food distribution center in San Francisco, Mr. Maxworthy started a program called Farm to Family, which distributes slightly damaged produce not fit for supermarkets or restaurants to needy families in California. It was Mr. Maxworthy’s accumulated experience, Mr. Freedman wrote, that allowed him to build a program that helped so many improve their diets.

Besides, finding new challenges late in life likely to prolong it.

Dr. Howard S. Friedman, coauthor of “The Longevity Project,” a study of well-being that followed people over eight decades, said taking it easy is overrated. “There’s a misconception about stress,” he told The Times. “A hard job that is also stressful can be associated with longevity. Challenges, even if stressful, are also a link” to a long life.

In the end, he said, “if people were involved, working hard, succeeded, were responsible - no matter what field they were in - they were more likely to live longer.” TOM BRADY