About four years ago, USBA Light Heavyweight Champion boxer Mike Lee found himself spending more time in hospitals than in the ring. He had been diagnosed with ankylosing spondylitis, an autoimmune disease that causes severe inflammation, chronic pain and fatigue. And the possibility that this disease meant the end of his career left him anxious and depressed.

Despite it all, Lee cited a moment during this time that shifted his mindset for the better. He recalled lying in a hospital bed in Chicago, hooked up to IV’s, wondering if he’d ever be able to fight again, when he peered out the window and noticed a couple kids playing in the park. “I remember thinking in that moment: ‘when I get out of here, I’m never going to take that for granted,” he said.

Doctors told him that he’d never be able to box again, or that if he did, it wouldn’t be easy. But Lee, a professional fighter in and out of the ring, refused to accept a future without boxing. He said his newfound sense of gratitude empowered him and gave him the strength to persevere through tough times.

“Now when I’m tired and sore during a training camp, I remind myself that it’s a gift that I get to train,” he said. “In the hours before a fight, when stress might creep in, I turn to gratitude. I’m lucky to be able to fight once again, to fight on the biggest stage and chase my dream of world champ.”

Every day, Lee takes a few moments to close his eyes and visualize three things he’s grateful for – a practice he said he learned from Tony Robbins. “Some days you don’t want to do it,” he admitted. “But it can be something as simple as the weather or talking to a loved one. The three things I’m grateful for today might be small, but tomorrow, they might be really big.”

Lee added that mindset is key, especially in athletics. “In the past, when situations didn’t go my way, I would get really down on myself, which would only exacerbate the pain and the situation,” he explained. “But practicing gratitude and keeping a positive mindset has changed my outlook on things like that.”

Though doctors say it’s a lifelong disease, Lee remains hopeful that he will win this fight. He is undefeated and ranked third in the world by the World Boxing Organization, and he doesn’t intend to lose just yet.

“[This disease is] something that hinders me in the moment, but I continue to get better,” he said. “I have some days that are definitely setbacks, but I know in my heart and my mind that I will figure out a way to completely beat this.”