When most people turn 50, they begin to think about slowing down.

It's the exact opposite for Pushpa Chandra. She's a 50-year-old mother, and marathon runner who is about to finish the year in the most challenging race ever.

Dr. Pushpa Chandra has marathon medals for races she's run all over the world.

The toughest so far was the Mount Everest marathon that she ran almost year ago.

But the one she is preparing for now could be even tougher. It's a 100 kilometre run across the interior of Antarctica!

"It's as you know, the coldest, driest, windiest and highest continent,'' she said. "

"About 98 percent of the world's ice is actually in Antarctica, so the terrain is going to be sheer ice."

If Chandra finishes what will be the meanest marathon of her career, she will be the first Canadian and the second woman in the world to do so. And at age 50, among the oldest.

"It's the new 20's. It really makes me feel like I am back in my 20's,'' she said.

"And there's this confidence that allows me to go push myself to different adventures."

First in her age group

Running in Antarctica in mid-December will bring her total this year, to five ultra-marathons on five continents, celebrating five decades of life.

"There is a desire for me to explore my limits," she said.

She isn't kidding! After training for months on the Vancouver's North Shore, Chandra began in 2008 by running the Mount Everest Marathon. It almost killed her! For several days, she struggled to breathe after suffering high altitude pulmonary edema.

"I was the sickest of the 75 athletes, and the sickest of the 13 who got evacuated. But I never gave up. I felt there was that mental desire, mental endurance that allowed me to get better."

Chandra rallied and ended up finishing first in her age group.

She isn't packing too much for the Antarctic race, as she will be renting an especially warm winter suit in Chile, before taking the flight over to the land of rocks and ice.

"It's exciting, it's challenging,'' she said. " It's very much a privilege to experience. I value that as well."

So in one year-- her 50th year-- Pushpa Chandra will have run from the highest peak to the lowest pole on what she feels is a spiritual journey in a beautiful world.

"It's an experience at all levels that gives me that drive to go on to the next level of my life."

With a report by CTV British Columbia's Peter Grainger