Rachael Malmberg has had a lot of tough challengers throughout her career as an ice hockey player, especially while playing with the world champion Team U.S.A.
Still, none of them compare to the deadly opponent she's had to face over the last couple of years: cancer.
Despite being what many would consider the picture of perfect health, the professional athlete ended up getting diagnosed with lung cancer two years ago.
At the time, Malmberg was healthy and fit so when she started experiencing symptoms like pain in her ribs, she chalked it up something else.
Unfortunately, by the time she was checked by a doctor, the cancer was at Stage 4.
Although she was devastated, Malmberg was determined to beat the disease, and part of that battle included looking into what could have caused it.
Through her research, Malmberg discovered that her inexplicable lung cancer may have been caused by a gas that we all breathe in everyday - Radon.
"It wasn't on my radar at all actually until I started doing research on causes of lung cancer. Upon diagnosis I had no idea about radon," Malmberg told Fox News.
Radon, an odorless, tasteless, and invisible radioactive gas, is usually "released from the normal decay of the elements uranium, thorium, and radium in rocks and soil," according to the National Cancer Institute.
While everyone inhales small quantities of it daily, overexposure to the gas is actually the second leading cause of lung cancer as it damages the cells that line the organ.
Approximately 15,000 to 22,000 lung cancer deaths are related to radon.
Malmberg believes that she was exposed to radon through the cracks in the walls or floors of her home.
Both her childhood home and the current one she shares with her husband and daughter in Minnesota have registered higher than normal levels of the gas, 7.9 Ci/L and 6.9 pCi/L respectively.
Radon levels of 4 pCi/L or higher should be reported, but Malmberg's family were not aware of the danger they were living with.
After testing her home, she installed a radon mitigation system to reduce the gas that's being diffused in the air.
"Now, I use the Airthings Wave for everyday testing to ensure continued safety and have an annual test conducted in the home to serve as an additional measure," Malmberg told Fox News.
As for the cancer, Malmberg had to undergo intensive treatment, including the removal of 22 lymph nodes and stereotactic brain radiation to remove a brain tumor. The medication costs $20,000 a month.
Malmberg, now the president of Cancer Survivors Against Radon, is sharing her story to raise awareness about the dangers of the invisible gas, and remind people to test their homes through a randon challenge she started.
"God gave me this journey for a reason. I may not know what it is now, but I feel like I'm being guided to be an advocate for others.
I want nobody else to go through what I've gone through," she said. "If that means sacrificing my time and my body, and my family's willing to support me through that, then I'm going to do it."
She's still undergoing therapy to control the cancer, and in the meantime, doctors are watching her brain closely because a small spot has developed on it.
However, she's not letting the setback slow her down. Malmberg has been training for a marathon that will be taking place this spring.