"I can't die — I'm booked."

That famous line from George Burns, who lived to 100, sums up the attitude of many chorus members in the documentary "Young @ Heart."

Death, of course, plays a role in the film about the chorus of 24 singers, whose average age is 80. But the Fox Searchlight movie is really a primer in how to live, experts on aging suggest. They say America's 77 million baby boomers could learn some valuable things from these smart elders.

"They are all deeply engaged in life. They show what many aspire to — to be active, passionate and engaged to the end," says Denise Park, a cognitive neuroscientist at the University of Texas in Dallas.

Park assigned her 10 lab employees to see the critically acclaimed movie. Although it doesn't sugar-coat health challenges, "the film eloquently presents some truths about aging, how to age gracefully, that we all should pay attention to," she says.

Among the scientific truths told amid the music and drama:

POSITIVE THOUGHTS OF AGING IS GOOD FOR YOU

In a landmark Yale study a few years ago, "adults who had more positive thoughts about aging, measured up to 23 years earlier, lived more than seven years longer than those with negative beliefs.

The survival difference remained even after taking into account health, age and other key qualities that affect life span, says psychologist Becca Levy, the study leader.

Negative views of aging may increase the heart rate and blood pressure of older adults under stress, Levy speculates.

Several chorus members outlived and continue to outlive doctors' predictions. Their determination to master the challenging music for shows reflects a "can-do" approach in later years.

"I'm continually shocked at how well (these) people do — they can do more than you think because they believe in themselves and keep trying," says Bob Cilman, 54, director of the chorus since it began 26 years ago in Northampton, Mass.

LAUGH, BECAUSE IT'S HEALING AND HEALTHY

Fred Knittle, a virtuoso singer who needs to use oxygen, tells the film's narrator/director, Stephen Walker, the secrets of his 54-year marriage: "We used to say, 'We stayed together for the sake of the kids — she didn't want them, and neither did I.' "

Another secret: "We went dancing twice a week — she went Tuesday, and I went Thursday."

Cilman at one point asks how many chorus members have been close to death, and several raise their hands.

He asks one, "Jean, did you see that white light everybody talks about?"

"I refused to look!" quips singer Jean Florio.

A lot of research shows that humor promotes quicker healing and better health, says Peter Sheras, a psychologist at the University of Virginia.

Laughter dissipates anxiety and lends perspective; both are helpful, as later years often bring more physical ailments, he says.

OLD AGE IS NOT A GOOD TIME TO BE A HERMIT

Evidence suggests that older adults are happier and healthier if they participate in groups that seem meaningful to them, says Lisbeth Nielsen, a program director in behavioral and social research at the National Institute on Aging.

Good relationships may prolong life because people are nudged by others to take good care of themselves, and they're more likely to do that if there are others they care about, says Sheldon Cohen, a psychologist at Carnegie Mellon University in Pittsburgh.

"We look out for each other, it's a close bonding," says chorus member Stan Goldman, 78, of Belmont, Mass.

And they count on one another: There are two rehearsals a week before a show.

In one of the film's most moving social scenes, the chorus travels way past the boundaries of sedate stereotypes about aging: Members sing at a prison, fanning out afterward to greet and hug the amazed prisoners.

MENTAL WORKOUTS KEEP THE MIND LIMBER

"There's growing research that learning new things in later years can help maintain and improve the brain, says Molly Wagster, a neurosciences branch chief at the National Institute on Aging.

Venturing beyond the comfort zone can bend the mind, Goldman says. He loves classical music, opera, Broadway tunes. But he has had to learn punk, rock and other "weird" stuff.

"I question many times the meaning of it — I don't know what the hell the music means," he says. Although the rhythm and words can be tough to master, "it's another dimension to my knowledge. It's kind of alien to me, but I'm enjoying it tremendously," he says.

PEOPLE NEVER OUTGROW NEED FOR A PURPOSE

"The question is, 'What gets you up in the morning?' These people care passionately about the group, and that's what keeps them going," Park says. Whatever it is that gives meaning to life, octogenarians need it, too, she adds.

Says Cilman: "You give somebody something they care about so much, and they're going to find a way to be there."

It's caring about something enough that matters in later years, Goldman believes.

"Don't cut yourself out of life because of your age," he says. "The movie projects a message people of all ages need to hear."