Pharrell gets emotional after watching inspiring video from his biggest fan

Nearly one year ago, Pharrell Williams sent an inspirational message to a 10-year-old boy named Damon, who was fighting cancer. Backstage at The Voice, ET shared a touching message from Damon to Pharrell.

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"Last year when I found out I had osteosarcoma bone cancer you sent me an inspiring video and when you sent me that, you might have thought that my arm was going to be amputated, but it didn't as you can see here," Damon told Pharrell in a video message. "And you also told me that I would do great things and inspire other people. You changed my life -- me and my family's -- I'll never forget that. One day I'd love to come up to you and give you a big hug and say thank you."

Damon is now a spokesperson for pediatric cancer and came up with the Happy Challenge, which asks people to share videos of themselves dancing to Pharrell's "Happy" to raise awareness for the disease.

"That's heavy," Pharrell said after listening to Damon's message. "I'm appreciative. I'm so proud of him. Dearest Damon, I just saw your message. I'm holding back the tears and emotion, but it's not a sad thing. I'm excited for you. I'm thrilled for you. As long as you keep your eyes and your attention and your heart on that, you can persevere and push through and continue to be a shining example to other kids who might be afraid, because you were very brave. Congratulations, Damon. We wish you all the best."

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Damon's father told ET that Damon still listens to "Happy" every day.

The Voicereturns to NBC on Monday, Feb. 23 at 8 p.m. ET/PT.

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