It's just emotions taking him over! Pharrell Williams was nearly moved to tears backstage at The Voice recently when he received a message, via Entertainment Tonight, from a young fan battling cancer.

The "Happy" hitmaker, 41, recorded a video for the fan last year, offering encouragement and well-wishes. In response, the boy — a 10-year-old kid named Damon Billeck — came up with the "Happy Challenge," which asked people to dance for 30 seconds to Williams' hit song in honor of Childhood Cancer Awareness Month last September.

Damon also recorded a "thank you" video for the Grammy-winning superstar, in which he recalled Williams' words to him after he was diagnosed with osteosarcoma, a form of bone cancer. "One day I would love to come up to you and give you a big hug and say thank you," he said in the clip, which ET played for Pharrell on a tablet.

The singer was visibly affected by Damon's words. "That's heavy," he said, clutching his heart. "I'm appreciative. I'm so proud of him. Dearest Damon, I'm standing here with Blake [Shelton] and [ET correspondent] Brooke [Anderson]. Just saw your message. Holding back the tears and emotion. But it's not a sad thing. I'm excited for you, I'm thrilled for you."

(Damon was apparently at risk of losing his arm, but doctors found a way to save it.)

"As long as you keep your eyes and your heart and your attention on that, you can persevere and push through and continue to be a shining example to other kids who might be afraid," Williams continued. "Because you are very brave...We wish you all the best. Trust me, man, my heart is beating super fast, bro. Godspeed."