Olympic gold medalist Kikkan Randall announced Wednesday that she’s facing her toughest challenge yet. The 35-year-old cross-country skier took to Facebook to reveal to her fans that she has been diagnosed with breast cancer.

“The color pink has taken on a new chapter in my life as I was recently diagnosed with breast cancer,” wrote Randall in her post, which featured pictures taken by photographer Charlie Renfro that showed off her indomitable smile during her first chemo treatment.

“Although we caught it early and the prognosis is good, my life will change quite a bit in the coming months.”

Randall, who called the diagnosis a “scary thing,” vowed to keep fans updated through her blog (www.kikkan.com).

She revealed that she is undergoing treatment at Providence Cancer Center in Anchorage, Alaska.

The 17-time U.S. champion began her chemotherapy treatments on Monday surrounded by friends and family, but not before squeezing in a workout and biking to the hospital, of course.

“I have promised myself that I will remain positive and active and determined throughout my treatment,” wrote Randall. “I am going to bring as much tenacity, strength, and energy toward this challenge as I have throughout my entire career.”