Let's tell Lucia McLain that she should wear a helmet when she hops on her bike for a spin to Mercy San Juan Medical Center, where she volunteers twice each month.

"I have one," says McLain, who's 93.

Of course! And here it is, unused, stored in the bottom of the china cabinet in the living room of her small apartment at the Atrium, a Carmichael assisted- living center.

"I use a cap with a shield to keep the sun out," says McLain.

A visor, she means, but that's hardly the point.

"She has done this for 60 years," her daughter, 71-year-old Lydia Simonette, says a bit wearily. Clearly, she's been down this conversational path with her mother a time or two before.

Gentle readers, when we reach our early 90s with the energy and vibrancy of Lucia McLain, we will have earned the right to insist with every fiber of our bossy hearts that she wear her bicycle helmet.

In the meantime, maybe we can learn something about active aging from her and Simonette, who belongs to a senior citizen tap-dancing troupe, the Classy Tappers, that performs a dozen times a year at local retirement facilities.

Today's active elderly – people 70 and older who are aging with grace and vigor – present a radical redefinition of what it means to grow older in America. Into their 80s, 90s and beyond, they're an inspiration.

A quick skim of Simonette's photo album reveals, for example, that troupe members not only wear adorable costumes but also have seriously great legs.

"People are surprised when they learn my age," says Simonette, who retired from state work in the early 1990s. "Chronologically, I'm in that elderly group, but it's not the way I look or the way I feel. I'm busier now than when I worked.

"I think 70 today is sort of like 55. People used to be old at 50."

No more, and thank heavens for that.

Granted, the age comparisons can become a bit too cute. If 70 is the new 50, and 60 is the new 40, then 30 is the new 10. And no one wants to dwell too closely on that possibility.

Looking at Simonette and McLain, who immigrated from their native Germany in the early 1950s after McLain married an American soldier, it would be easy to conclude that genetics determines destiny.

But gerontology expert Dr. Robert Butler, founder and president of the International Longevity Center-USA, says that genetics accounts for only 25 percent to 30 percent of healthy and active aging.

"That means 70 to 75 percent is up to us," he says. "Not smoking. Maintaining a proper diet. Exercise. Not drinking too much alcohol."

He should know: At 81, the New York-based Butler has a new book in print, "The Longevity Revolution" (Public Affairs, $30, 608 pages), and he walks a dozen miles with friends each weekend.

Other factors contribute, too. Getting old doesn't have to involve growing frail and sick. As one measure of that, according to the National Institutes of Health, research and treatment advances have reduced deaths from heart disease and stroke by 60 percent in the past 45 years.

California Department of Aging statistics indicate that the numbers of the "oldest old," those 85 and older, are expected to increase more than 150 percent by the year 2020 in Yolo and Sacramento counties – and more than 300 percent in El Dorado County.

Just since 2000, the ranks of the oldest among us across the region have grown by 50 percent, according to U.S. Census figures.

For active people with sufficient health insurance and pension coverage, living a long, long time is a gift. That's what Florence Hardy, an 83-year-old who lives in Davis, has come to think.

"I try to learn something new every day," she says. "A lot of people just don't do anything, but we're very busy every day."

Hardy's a newlywed, having married a retired 84-year-old computer specialist named Don Grotjahn on Oct. 23.

"We're very healthy," she says, and then she laughs. "We're happy, too. Umm-hmm. Oh, yes. That's us."

And good for them. So let's not overlook the role that emotional connections – to other people and the community, as well – play in promoting longevity.

A sense of purpose counts.

"Purpose is very important in robust, healthy aging," Butler says. "We don't think enough about that. I'm talking about caring about the grandchildren or even caring about whether the local football team wins.

"Purpose and a social network and friendships are very important."

In Carmichael, 82-year-old Gloria Cox plays tennis three times a week with a group of fellow seniors.

"It keeps people going," she says. "It gets them out of bed. They're not in wheelchairs."

A retired teacher and librarian, she puts on puppet shows for local elementary schools with fellow members of Sacramento's Assistance League. And she spends winters in Hawaii, away from the cold and fog.

"I walk a lot when I'm there," she says. "I take an apartment on the beach, and I audit a class at the university."

The notion of wintering in Hawaii is enough to make the rest of us want to segue into healthy retirement as soon as possible.

Lucia McLain's old age has been more settled, if still abundantly active. Until July, she lived in her own home, and she mowed the lawn herself.

"She had a cherry tree in the yard, and she always climbed a ladder and picked cherries," says her daughter.

"I don't miss the work," McLain says.

Even so, she continues biking 10 miles round trip to her Mercy San Juan volunteer duties, sewing Snoopy dolls for ailing youngsters. And she always spends Saturday mornings at Simonette's house, cleaning.

"We've done that every Saturday for 50 years," McLain says.

"And then we'll run errands or go grocery shopping," says Simonette.

Like mother, like daughter: They're too busy to slow down long enough for their age to catch up with them.

Call The Bee's Anita Creamer, (916) 321-1136.