Canada has an astounding 7.1 million grandparents right now -- more than at any time in this country’s history. And researchers are finding that all those seniors living healthier, longer lives are changing the makeup of the modern Canadian family.

Marjorie Leslie, 62, is one of those grandparents. At a point of life when many seniors her age want time for themselves, Leslie and her husband Milton Wong, 64, devote several hours every week to minding their two-year-old grandson, Evan.

“I love being a grandparent,” Leslie says, “It has brought so much joy to our lives.”

Rachel Margolis, a sociology researcher at Western University in London, Ont. recently completed one of the first studies in Canada and the U.S. on the huge shift in “healthy grandparenthood” – that period during which grandparents and grandchildren are both fit and well and can build strong relationships with each other.

Margolis found that even while today’s parents are delaying parenthood and waiting longer to have children, the grandparent period is also getting longer -- simply because seniors are living longer.

Margolis’ study found that middle-aged dads can now expect to be grandparents for 19 years, with at least 14 of those years as “healthy” grandparents. Mothers can expect to be grandmothers for 23 years -- the majority of it healthy. That long period is allowing many grandparents to live long enough to build close and lasting relationships with their grandchildren.

“Grandparents have significantly more healthy years overlapping with grandchildren than they did two decades ago,” she wrote along with co-author Laura Wright, of the University of Saskatchewan.

Margolis she was inspired by her own grandparents. Although two of them died before she was born, the other two lived until her adulthood – one died when she was in her 20s and the other when she was in her 30s.

“I feel like my grandparents offered a lot of support for development. I was close to them well into adulthood,” she says, adding that they pushed her academically and encouraged her to shoot for the top universities.

With the growing ranks of grandparents has come a boom in “grandparenting” guides: books, videos, and online communities offering tips for how to become a "wonderful grandparent.”

Young parents are also reaping the benefits of this growing trend, noted in the study, as grandparents give them a break from child care during their critical career-building years.-

Having a grandparent in a child’s life brings its own benefits. Studies show that grandchildren with emotionally engaged grandparents develop more “better social behavior and do better at school.

But the kids aren’t just benefitting from healthy grandparents; Leslie says her grandkids help to motivate her and her husband to keep fit and active, which makes her better able to play with them.

“You want to know you are still strong enough to run and teach him all the things you want to,” says Marjorie Leslie.

With a report from CTV medical specialist and producer Elizabeth St. Philip