When Marjorie Coppock suffered a massive heart attack during an aerobics
class, the assembled students would have been forgiven for thinking her days as an instructor were numbered.

After all, Marjorie was 85.

But just two months later the super-fit great-granny returned from
triple-bypass surgery to once again put them through their paces.

Five years on - at 90 years young - she's still going strong.

"I just love it," says Marjorie of the twice weekly fitness classes that
attract up to 50 women between 10 and 60 years her junior.

"It's something to live for. It's my life."

Marjorie has already outlived the average Australian female by six years, but it's the enduring vitality that leaves her ageing peers breathless.

Twice as fit as most people half her age, the Melbourne widow is also one of thousands of older Australians exercising the minds of the nation's health service bureaucrats.

Today there are 400,000 people aged over 85. By 2050, that number is
predicted to rise to almost two million. And 78,000 of them will have
reached three figures, compared to today's 2,900 centenarians.

Against a backdrop of rising obesity rates, fitness experts warn today's
younger generation cause most concern.

"Gyms used to be full of 20 to 35-year-olds, but now you're more likely to see people between 35 and 70," says Sydney-based trainer Tani Ruckle.

She's worked in the industry for 30 years, and won silver in the marathon at the 1990 Commonwealth Games in Auckland.

"A lot of older people are now really taking care of themselves, but young people are probably being less active," says Ruckle.

"It used to be that mum and dad would send the kids out to play so they
could have a couple of gin and tonics.

"Now it's the parents who are heading off to the gym while the kids stay at home playing video games."

Ruckle, 47, describes the difference between an active senior and one who doesn't exercise as "chalk and cheese".

Few remain as mobile as Coppock, who also helps children at a local primary school with literacy every Friday morning.

"I love children, they earth you," she says. "It's all very fine talking to middle and older aged people but I think it's important to engage with the young ones.

"I learn more from them than they do from me, I can assure you."

But Marjorie says today's young folk lack the crucial factor in longevity - discipline.

"My mother and father were exceptionally strong, and I had a very
disciplined childhood," she says.

The daughter of a Russian dancer and Australian acrobat who met on Broadway, Marjorie has been exercising and dancing as long as she can remember. She has never smoked or drunk alcohol, and believes good genes helped stave off many age-related ailments.

Recent research suggests strong relationships and spiritual beliefs, as well as exercise and diet, are crucial factors in living long and healthy lives.

After giving birth to two daughters, Marjorie, who tips the scales at just 45 kilograms, began teaching calisthenics in 1950.

During an aerobics class five years ago she collapsed.

"There was no reason for it, I don't think I'd taken a pill for anything in my life," she says.

"I didn't feel so good that day but there was no pain, no nothing. I don't actually remember very much but I was fortunate there were some medical people in the class."

Rushed to the city's Cabrini Hospital, Marjorie underwent a triple-bypass operation, but amazed surgeons with her return to fitness classes just eight weeks later.

Today she lives alone in the suburban Melbourne house she has called home for 70 years, and drives to a local community centre to teach Pilates, stretches and dance.

But she is frustrated by doctors' orders to refrain from aerobic activity.

"My heart is not what it once was and I have to take rotten pills," she
says.

"I am not allowed to do certain things, but apart from the aerobic
exercises, I can still do practically all the other exercises."

And there are no plans to stop.

"I have very strong faith and a wonderful church," she says.

"When the Lord says it's time to go, then I'll go."