Trevor Sullivan, 15, was diagnosed with severe cardiomyopathy in February 2015.

His family said the teenager wasn’t feeling well for about a year, but they thought it was just allergies. Then, in February 2015 his heart suddenly failed, and he had to be airlifted to C.S. Mott Children's Hospital in Ann Arbor, Michigan.

Soon after, Sullivan was added to a heart transplant list. In November the family finally found a donor, and months later, the teenager would complete the transplant surgery.

Sullian's mother filmed the first few moments after he woke up, and his reaction is remarkable.

"I’m so happy," he said in the video. "I’ve been waiting so long. I can breathe again and talk. I feel amazing. I’ve never felt so good."

The video was posted to the C.S. Mott Children's Hospital Facebook page, where it racked up tens of thousands of views.

Sullivan said he’s happy so many people have seen the video and hopes that more people sign up to become organ donors.

The family has set up a GoFundMe page to raise money to cover medical expenses.