Samuel Johnson on why he never had children of his own, and perhaps never will.

After Samuel Johnson took away Australia’s top gong at last Sunday’s Logies, focus has firmly shifted onto his family. Or, most notably, the relationship between the actor and his sister Connie, who is battling terminal cancer.

In an interview with TV Week, Johnson has shared why he has never had children of his own, and why he perhaps never will.

“I’ve had kids in my life my whole life,” he says. “I don’t really need to squeeze my own out to have them,” adding he may have left his run too late anyway to have some of his own.

“I’m going to be 40, I’m too old,” he told the magazine. “I’ve moved out to the bush. I’ve retired. There’s no chance of kids.”

But most importantly, he does have two children to think about. Connie’s two sons, Willoughby, 10 and Hamilton, 9.

“Connie’s got some pretty important jobs for me when it comes to her kids once she’s gone,” he says. “I’ve got to make sure I get everything right.”

Willoughby and Hamilton were just three and four when their mother was told she had breast cancer.

Connie, now 40, is facing her final few months with her sons and told ABC’s Sunday Brunch last week she is focused on spending “quality time” with her family.

"I thought I would only live six to 12 months when I was first diagnosed, so it's been amazing to have that extra time with my family," she said.

"The first thing I thought when I got diagnosed was, 'My kids won't remember me'. I really wanted them to grow up to an age where they remembered me...not just from photos and stories people told, but actually have their own memories.

"My wish was that I could get through to an age where [they were old enough] to remember me and that has happened and it's been absolutely wonderful."

Connie, Sam and Love Your Sister are focusing on one last fundraising effort - to raise another $1 million for breast cancer research.

On May 10, Love Your Sister has organised the Big Heart Project to take place in Canberra to create a giant love heart made from five cent coins. The idea is to create an unofficial world record, but more importantly raise money for breast cancer research and awareness.