Zach Sobiech is dying with grace, love, joy and optimism -- the kind that somehow makes us all feel more alive.
When he was 14, Zach was diagnosed with osteosarcoma, a type of bone cancer that mostly strikes children. His prognosis wasn't great. Last May, with no more treatment options, he was given just a year to live.
Zach turned 18 on Friday. On Saturday he went to prom with his girl, Amy. His high school class graduates next month.
Zach began writing music after his cancer was diagnosed. His mom, Laura, was cleaning the family room downstairs last year when she found a folded-up piece of paper. She unfolded it to make sure it wasn't a homework assignment.
"I read through it and then I realized what I was reading," she says.
It was his first song, "Clouds." Zach wrote it for himself and his family. He has since written many more.
"I fell down, down, down into this dark and lonely hole," he sings at the beginning of the song.
His voice is beautiful, mellow -- kind of reminiscent of Jack Johnson's.
When Zach's song was posted to YouTube it quickly went viral, getting more than 2.6 million page views.
Now there's a new video you ought to see. On Monday, dozens of celebrities posted a love letter response -- joining forces to lip sync to Zach's voice, singing "Clouds."
"And we'll go up, up, up, but I'll climb a little higher," sing Jason Mraz, Anna Faris and Rainn Wilson.
"Go up in the clouds because the view's a little nicer up here, my dear," sing Bryan Cranston and Rachel Bilson, Ashley Tisdale and Colbie Caillat.
"It won't be long now," sing the Lumineers.
"If only," sings Sarah Silverman, "I had a little bit more time."
It's a hello to Zach, and a farewell. It's a collective expression of love and gratitude.
The motley crew of celebrities on the video was assembled by Wilson, an actor, and director/actor Justin Baldoni, who directed a short documentary about Zach for his compelling online reality series, "My Last Days," which runs on Wilson's SoulPancake YouTube channel.
"Going out to see Zach in Minnesota was one of the greatest experiences of my life," says Baldoni. "To make the choice to be happy despite whatever sad or tragic circumstances you may be living through ... he is this old soul who inspires everyone he meets. You leave and you think: 'I want to be a better person.'"
Watch Baldoni's film and you can see why.
There's Zach, a fresh-faced Minnesotan teenager, in one of the opening frames, saying: "I want everyone to know: You don't have to find out you're dying to start living."
He tells us at the beginning of the film: "You know most people live kind of in the middle, in between 'all your dreams come true' and 'you're dying,' and it's a very comfortable place to live. I'm living on the two extreme ends, so you have really, really good days and you have really, really bad days."