Get the latest from TODAY
Thomas Walsh had put aside his dream of becoming a ski racer after a childhood cancer left him with a permanent limp nine years ago.
Then he watched his lifelong friend Mikaela Shiffrin win a gold medal in the slalom at the 2014 Olympics, reaffirming his love of the sport and fueling a drive to compete in this year's Paralympics in Pyeongchang.
As he stood on a hill in South Korea after his first race on Sunday, Walsh, 23, fought back tears after an emotional Shiffrin delivered a heartfelt message to a friend she has watched overcome so much.
"I wish I could hug you right now and tell you that we're so proud of you,'' a tearful Shiffrin said.
"You look at me now and I'm standing here talking to you, I look pretty normal,'' Walsh said after seeing her message. "Mikaela was there when I was really in the dumps, and life was really uncertain, so that means a lot."
Walsh and Shiffrin, 22, both grew up skiing in Vail, Colorado, with Shiffrin's mother, Eileen, serving as Walsh's first ski coach when he was 6 years old. Even after Shiffrin's family moved to New Hampshire when she was 8, the two remained friends.
Walsh was an up-and-coming star at 14 who was set to attend a ski academy in Vermont in 2009 when he was diagnosed with Ewing's sarcoma, a rare cancer that grows in the bones and soft tissue around the bones.
He had parts of his pelvis and lungs removed and underwent chemotherapy, with one doctor telling him he would never ski again, according to The Denver Post.
Shiffrin helped Walsh fight through the depression over the loss of his ski career by making a deal with him that they would go to prom together when he was done with his treatments.
Her ski school in Vermont didn't have a prom, so she went with Walsh to the one at his school in 2012.
"She looked gorgeous," Walsh told NBC Olympics. "Everybody else at school was jealous that I was Mikaela's date."
Walsh began to recapture his drive to be a ski racer when he watched his friend's dazzling performance in person in Sochi thanks to the Make-A-Wish Foundation.
Once he realized he was eligible to compete in the standing classification of Para Alpine due to the deficiency in his leg, he worked to qualify for the Paralympics.
He will compete in the super-G, giant slalom, alpine combined and slalom at the Paralympics from March 9-18. He hopes to bring home a gold medal just weeks after his good friend won the giant slalom in Pyeongchang to take home her second Olympic gold.
Shiffrin is rapidly becoming a legend in her sport after winning her 42nd career World Cup race over the weekend and capturing her second overall World Cup title. But to Walsh, she is so much more than an amazing skier.
"Mikaela may be a champion and a star and international hero...and I would even say the greatest female ski racer of all time," Walsh said. "But above it all she's just one of my good friends."
Coverage of the 2018 Paralympic Games continues through Sunday March 18th on NBC SN and Olympic Channel: Home of Team USA.
Follow TODAY.com writer Scott Stump on Twitter.