It's called the World Marathon Challenge, and it's basically the big Kahuna of running events. First launched in 2015, the World Marathon Challenge involves running seven marathons on seven continents over the course of seven days. Even for the most seasoned runners, this is no joke. It involves feats of mental and physical endurance that would hobble even the strongest competitors.

At the end of January, 47-year-old BethAnn Telford plans to complete this enormous endurance event. She won't be the first American or even the first woman to tackle this challenge, but she will be the first to do it with a malignant brain tumor.

For most people, the idea of running a marathon is an enormous goal. A marathon covers a distance of 26.2 miles and requires weeks and sometimes months of mental and physical training to complete. At the end of this month, Telford and 32 other competitors from around the world will attempt to run not just one marathon but seven of them over the course of a week while jet-setting along the way.

The specs of the race

The World Marathon Challenge's week of multi-event races begins in Union Glacier, Antarctica, on Jan. 23. From there, Telford and her fellow runners will hop on a plane to Punta Arenas, Chile, followed by Miami, Florida; Madrid, Spain; Marrakech, Morocco; and Dubai, United Arab Emirates. They will run a marathon in each location. The final marathon will take place in Sydney, Australia. on Jan. 29. In all, the athletes will spend almost 60 hours in flight covering 23,600 miles.

In 2015, 10 runners — including only one woman — completed the World Marathon Challenge. In 2016, there were 15 finishers, four of whom were women, including Becca Pizzi, the first American woman to complete the event. This year, those numbers will more than double as 33 athletes show up to complete this mega-marathon challenge. Telford will be there, raising money for charity with each step.

Why is she doing this?

Telford is an ambassador for the Washington, D.C., nonprofit Accelerate Brain Cancer Cure, an agency focused on finding a cure for pediatric cancer.

"Since I wasn’t able to have kids, I’ve 'adopted' hundreds and hundreds of children [with pediatric cancer] where I’ve tried to instill in them, and their families, that there’s hope," Telford told "Good Morning America".

To date, she has raised $835,000 for the cause, but she hopes that by running the World Marathon Challenge, she will raise her profile, allowing her to top the $1 million mark.

It won't be easy. Not only will Telford have to keep up this furious pace, but she'll also have to do it while struggling with the diminished stamina and bladder capacity, partial blindness, and risk of seizures — all side effects of her disease.

But for a woman who has been through chemotherapy, brain surgeries, and looked death in the eye, Telford knows she's up to the challenge.

"I know I can do this. It’s just one step in front of the other."

Check out Telford's World Marathon Challenge charity page for more info and to help her raise funds for pediatric cancer research.