(CNN) -- Sixty used to be old -- or at least it seemed to be.
In the '80s, seniors had TV role models like the Golden Girls, Matlock and "Murder She Wrote's" mystery-writing sleuth, Jessica Fletcher.
Harrison Ford may be 65, but he still fits into Indiana Jones' trousers from 1981.
Now baby boomers can look to Goldie Hawn, Diane Sawyer and Harrison Ford for inspiration as they near retirement age.
Today's seniors also have a much different view of fitness than their parents, said Colin Milner, CEO of the International Council on Active Aging.
"Exercise was actually a bad word," Milner said. "The term exercise meant hard work. It was what you did in the military or body builders did at Muscle Beach and women were told that if they did it they weren't womanly or it would hurt their reproductive organs."
Milner said baby boomers helped spark the modern fitness movement. See photos of celebrities, politicians and sports legends over 60 »
He said 37 percent of health club members are 55 or older, and that doesn't count people who work out at retirement homes -- an area he said is exploding.
"Nine out of the 10 top builders in the U.S. are building active adult communities and they will typically put in anywhere between a 20,000- and 40,000-square-foot fitness center."
The average age of personal training clients also is going up, from 36.5 in 1998 to 42.4 in 2006, according to Robyn Stuhr of the American Council on Exercise.
The council certifies fitness professionals and has partnered with the AARP to help match the group's 38 million members with personal trainers.
"Our trainers say they're starting to see more middle-age and older clients and we've actually been looking at developing more curriculum about working with those groups," she said.
Stuhr said older clients are at higher risk of diabetes and cardiovascular disease and also may have problems like arthritis, back pain or muscle tears.
"That probably means you need to exercise even more, but the trainer has to understand how to work with that population and make exercise a safe experience," she said.
She recommends getting a good physical before starting an exercise program and says people need to realize that their bodies aren't the same as they were when they were 20.
"Exercise can be a fountain of youth, in that it can help slow down aging changes and help you maintain a level of vitality and energy that you might not otherwise have. But you just have to do it smarter, because your body is more vulnerable because of the aging process," she said.
Milner says he's spoken to many physical therapists whose patients are pushing themselves too hard.
"What's happening is more of the boomers are going out and beating the heck out of themselves as a weekend warrior and spending the rest of the week in therapy," he said.
"Some wonder what kind of therapy they should be in," Milner said jokingly.
But that doesn't mean seniors have to take it easy.
Dr. Walter Bortz, author of the books "Dare to be 100" and "Living Longer for Dummies" is 77 years old, but he has run a marathon every year for the last 35 years.
"You're supposed to be a little bit tired," he said, but people should avoid "undue fatigue."
"Obviously, pain is nature's signal, but you can't be a pantywaist about pain," said Bortz.
Better stretching, going a little slower and investing in new shoes are just a few tips he offered, but he also encourages boomers not to give up.
"Fitness for young people is an option, fitness for old people is an imperative," Bortz said.
The government's National Institute on Aging says regular activity can help seniors maintain their strength and be more independent, have more energy and better balance. Exercise can also help reduce depression and fight diseases such as heart disease, diabetes and cancer.
It recommends that seniors focus on four types of exercise:
The bottom line is people can benefit from exercise no matter how old they are, according to the International Council on Active Aging.
"In the fitness industry, there's the old saying 'use it or lose it,' " Milner said. "But even if you've lost it, you can still find it again, no matter how old you are."
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