- Kate Foster started doing gymnastics at age 6
- She was diagnosed with leukemia at age 12
- She's competing again after losing her leg
(CNN)Kate Foster started gymnastics when she was 6 years old.
"I tried soccer, I did karate and then I started gymnastics and that really clicked with me. I loved it," she said.
"You know you've got the right sport for your kid when they don't complain about having to go -- they really want to go," said her mom, Barb Foster.
By the time she was 11, Kate was practicing for 25 hours a week at the gym.
But then she started feeling sick off and on for several months -- and the symptoms wouldn't go away.
"I just felt terrible all the time. I was tired, and I got a bunch of bruises. Then I started getting staph infections. That's when we were like, 'Something's wrong here,'" Kate said.
A blood test revealed she had acute myeloid leukemia. The doctor broke the news to her parents.
"We packed our bags and her bag. Kate was still at the gym," her mom said. "We drove directly to the children's hospital. They had a room waiting for us."
Kate started chemotherapy immediately, and it wiped out her immune system.
"One of the reasons why my hospital stays were so long was because of my complications. My first hospital stay, I got a gangrene infection," she said.
"All of a sudden, we went from cancer patient to she was on life support for three days," her mom said.
During her second hospital stay, Kate got another infection in the same leg and ended up in the intensive care unit. By her third round of chemo, before her bone marrow transplant, doctors found an infection in her knee joint.
"That's when they finally said, 'We have to amputate,'" Kate recalled. "I was devastated. I actually told them no. They were not going to take off my leg. ... Then I came to my senses. I knew, and my family knew, that it was my leg or my life."
At that point, said her dad, Lynn Foster, "She started crying, and she said, 'What about gymnastics?'"
Then Kate's coach said something to her that really changed her mindset.
"She said, 'I've never taught a one-legged gymnast before, but I'm willing to try if you are,'" Kate said.
That motivated her to get back to the sport she loved.
"Kate is all driven from the inside," said her coach, Denise Cooper. "I think that's what made her such a great fighter against leukemia."
Kate went back to the gym for the first time on her 13th birthday. She started out conditioning and regaining her strength. Once she got her prosthetic, she began working on her events and getting her skills back.
"I wasn't going to let cancer change what I did and what I was going to do," she said.
Now she competes against able-bodied gymnasts in two events on bars and beam.
"They do not change the rules for her, which is fine with her," her dad said. "She doesn't want the rules to be changed."
In January, Kate's dad videotaped her bar routine during a competition and posted it on Facebook.
The next day, the video had been viewed 100,000 times and the number kept going up. Now it's up to more than 5 million views.
"She's the epitome of 'It doesn't matter what bump in the road you hit, you can still make things work,'" he said.
Now a senior in high school, Kate has been cancer-free for more than three years.
"I would like to be a doctor when I grow up," she said. "With all my experiences and the doctors who helped me and saved my life, I can't think of a better way to repay them than helping other people and possibly saving another person's life."