Woman With Brain Cancer to Run 7 Marathons on 7 Continents in 7 Days

— -- One woman is set to tackle an amazing feat -- running seven marathons in seven days on seven different continents.

That accomplishment would be amazing in itself. But for BethAnn Telford, who says she continues battling brain cancer, the task is awe-inspiring.

Telford, 47, said she was diagnosed with brain cancer in 2005. After "several brain surgeries," she told ABC News that she still has active cancer cells in her body that affect her in a number of ways.

She said hasn't driven in 12 years because she has seizures often "and I have no sight in my left eye." Her brain cancer also affected her bladder, she said, which led to a surgery for a major bladder augmentation.

Telford said her bladder is one of the things she has to really keep an eye on when participating in the 2017 World Marathon Challenge that has 33 participants from 13 different countries competing. Over the seven days, they'll each spend 59 hours in flight spanning more than 23,600 miles.

"My bladder can only hold a shot glass of liquid," she explained. "I self catheter so when I go to the bathroom ... during the marathons, I just don’t go into the jiffy pot. I have to keep it clean and sterilized."

The first marathon is in Union Glacier, Antarctica, on Jan. 23. Telford and the other competitors will then run in Chile, the United States, Spain, Morocco, the United Arab Emirates and Australia.

Telford knows she won't be the first to cross the finish line. For Telford, her participation is much bigger than winning.

Telford, who started running marathons 15 years ago, said she's running to raise funds for pediatric cancer research. It's especially important for her to invest in children.

"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," she said. "Their last stop is the hospital. They don’t come home with their parents, unfortunately, and it saddens me that we can’t find a cure."

During the marathons, Telford said she'll be running with pictures of those children clipped to her race belt. She'll also be wearing New Balance running shoes, decorated by the children.

"I know that when I look down, these kids are with me and that's what's going to get me through this," Telford said.

The government worker, who lives in Washington, D.C., has been training four times a day to prepare for these races.

"I wake up at 3:30 in the morning, run, or I do core strength training," she detailed. After going to work, she'll finish the day by doing yoga or swimming.

Since 2005, Telford said she's raised more than $835,000. But with these series of marathons she hopes to cross the million-dollar mark.

She'll be donating the funds she raises to a Washington, D.C.-based non-profit Accelerate Brain Cancer Cure, co-founded by Steve and Jean Case. Steve Case is also known for co-founding AOL.

"It means so much to the entire brain tumor community across the world because what BethAnn is doing is raising awareness about this devastating disease," Nicola Beddow, Director of Communications and Partnerships for Accelerate Brain Cancer Cure, told ABC News. "And then she’s also raising dollars for research; we invest in cutting-edge research to develop new treatments for brain cancer because sadly they’re just not enough right now."

Along with raising money, the marathoner wants to spread hope. The word "hope" is so important to her that she has it tattooed on her left inner wrist.

"This is not a tough endeavor for me. It sounds like it is, but the toughest thing in my life to date, at 47, is telling my mother and father that their child has brain cancer," Telford said.

"Nothing compares to that -- going through chemo, brain surgeries, and even [facing] death," she continued. "I know I can do this. It’s just one step in front of the other."