How are so many seniors able to remain so active?

Although Gloria Struck is one of 22 women profiled in the book Biker Chicz of North America, the 87-year-old prefers to be called a motorcyclist. The Clifton, N.J., native did, after all, just return from a trip to South Dakota, putting 4,372 miles in seven days on her 2004 Heritage Softail Classic.

"It was marvelous!" said the churchgoing mother of two.

Across the Schuylkill in London Britain Township, Chester County, Tom George is waxing his skis. The 83-year-old spent the summer racing his 30-foot sailboat on the Chesapeake Bay and will barely have time to clean the barnacles off his boat before the downhill season starts.

On the Cooper River, Jerry Jerome and his crew are stepping out of their boat. The Cherry Hill resident still gets a thrill every time he races, but he does have to exit the eight a little more carefully than his younger teammates. He's 76.

Everyone knows that 60 is the new 40, that seniors take cruises and ballroom dancing lessons, and that the gym is as much a part of this generation's life as their morning fiber cereal.

But considering that seven days on the road might take a toll on a 50-year-old, or that black-diamond slopes might daunt a twentysomething, it's hard to deny these folks some admiration, not to mention wonder: How do they do it?

"They had that healthy lifestyle throughout their younger years and built up stamina and endurance," explained Dyanne P. Westerberg, chair of the Department of Family and Community Medicine at Cooper Medical School, Rowan University, and Cooper University Hospital. And movement begets movement.

"Exercise throughout our lifetime improves our physical abilities and helps our strength and range of motion, so we can continue activities as we get older," she said. "Once people continue on this path, they're able to maintain this active lifestyle into their upper years."

Struck began riding a motorcycle at her brother's urging when she was 16. "I never wanted to ride a motorcycle, but we were in the motorcycle business, and my brother decided I should," she recalled. Her father owned the Lexington Cycle Shop, a motorcycle and bicycle dealership he started in 1915 in Clifton, which she helped run during World War II.

Passersby might think cruising on a Harley is a breeze, but it's no small task to command a big bike.

"My motorcycle is 750 pounds," said Struck, a former Avon representative for 44 years, who wears her white hair in a bun. She also worked for Bendix Aviation Corp. making radar and autopilots for planes.

"It takes some muscles to ride and balance, and a lot of alertness and attention."

George came to skiing in 1947 as a college freshman, and these days, from January to March, his Weekday Skiers Club makes regular Tuesday bus trips to resorts in the Poconos. It's their way to gear up for their annual weeklong getaway at the end of the season. This year, they'll ski in Okemo Mountain Resort in Ludlow, Vt. "I like to be in good shape when I get there," said George, who, at 5-foot-10 and 170 pounds, might rival the physique of men half his age.

Though these days he avoids tough-on-your-knees moguls, George still hits the black-diamond trails. "What I really get pleasure in," he said, "is swooping down the mountain."

He also appreciates the social aspect. The ski club goes on outings in the summer. About 15 boats participate in races, and then afterward, they have a beer and talk it over.

When not sailing or skiing, the retired research physicist plays duplicate bridge and builds furniture in his workshop. He's also setting an example for his three children and six grandchildren, who spend time with him on the water and the slopes. "They've had a lot of exposure to the things I think are fun," he explained.

George has taken many incredible ski vacations, and tops on his list was skiing Ischgl, Austria, two years ago - an adventure that gave new meaning to "cross-country."

"It has 70 miles of wide trails groomed perfectly every night, plus vast areas of off-piste skiing. One long run takes you to a neighboring town in Switzerland."

If that sounds fun to you, but you're reading this from a couch, George has advice.

"Just because you haven't done it before, don't hesitate to try it now," George said. "I have friends who took up skiing in their 60s who had never skied before."

That said, be cautious and take it slow, said Westerberg. "I wouldn't want anyone to go into these full-blown physical activities without a checkup by a medical doctor first."

Health benefits aside, physical activity just feels good. Known as a runner's high, endorphins are released during exercise.

"It gets in your blood," Jerome said of the feeling he experiences from rowing. He especially enjoys the competition that racing provides. "It's not competitive in the sense that I have to win, yet you want to win. We're generally novices."

The retired telephone-industry salesman and manager originally discovered rowing through a basketball buddy. As a 22-year-old, he joined the Penn Athletic Club. A move out of the area led to a 50-year hiatus, until he discovered the Rutgers Alumni Rowing Team five years ago and decided to start up again. "It was like I never stopped," said Jerome, who also coaches the Camden Youth Soccer Club.

It's a fun way to exercise without putting stress on his knees. "There is something vitalizing about being on the water, and an inspirational part of my rowing is that I do not think of myself as 76."