While most high school seniors have spent the school year looking ahead to the future, terminally ill Lakeland, Minnesota teenager Zach Sobiech has spent his time staring down the unimaginable.

As his classmates made plans for prom and filled out college applications, Sobiech and his family juggled two unexpected, alternate realities: Zach’s bone cancer had started spreading so rapidly that he knew he may not make it to see graduation, and Zach had suddenly become a commercially successful and celebrated singer/songwriter with fans around the world.

It was three and a half years ago when Sobiech’s life changed forever. In the summer before entering high school he went out for a run and came home with a sharp pain in his left hip. What was initially thought to be an issue with his hip flexor was eventually revealed to be a tumor, and when he was just 14 he went from getting ready to try out for the Stillwater High School basketball team to coming to terms with the fact that he had osteosarcoma, a rare form of bone cancer that specifically afflicts children.

After countless surgeries and rounds of chemotherapy and radiation, the Sobiech family received the worst news of all: Zach’s cancer had spread into his lungs, and his prognosis had turned grim. The family was told that Zach might only have a few months left to live.

“Zach’s mom Laura, who is just a beautiful person and has really worked so hard to hold her family together through all of this, told Zach look, you’re not good at writing letters, I think you need to do something that leaves something for the people that you love, that helps to give them a memory, something they can hold onto,” Rock the Cause founder Scott Herold recounts.

“Zach’s a guitar player, and he started writing songs for his family. And the first song, ‘Clouds,’ he sketched out, and his mom saw the lyrics laying on a table and said this is really good, this is my kid’s music. And like any loving, supportive mom—fiercely supportive mom—she went out and started finding the people to bring it all together.”

When she first heard ‘Clouds,’ Zach’s mother, Laura, reached out to radio station KS95, whose Vice President Dan Seeman was so touched by Zach’s story that he rounded up a handful of recording engineers and studio musicians to help give “Clouds” the professional treatment it deserved.

A local video production company, Wooly Rhino, came to the studio while Zach was recording “Clouds” and created a music video to accompany the song. Within weeks of first posting it, the video took off and became a viral sensation. Since it went live in December of last year, “Clouds” has been watched nearly 3 million times and has been featured by media outlets around the world.

“The song is fantastic,” says Herold, who stepped in once “Clouds” started to go viral and helped the family set up a way to distribute his music. “And the story behind it: Here’s this young man that is taking music, and facing this with courage, and with grace. I saw the comments that were happening around the world, I saw drug addicts, and I saw people who wanted to commit suicide leaving comments on Facebook and saying, ‘I’m inspired, I want to keep going.’”

Zach’s childhood friend Sammy Brown says she isn’t surprised that music has played such a significant role in his illness.

“It’s really a way for him to express things,” she says. “He’s not one to have deep conversations all the time, because that gets so heavy. But when he writes a song, it’s his way to communicate to a single person or a large group of people, and people really can relate to that and I think it makes him feel better.”

Brown and Sobiech started making music together when they were 12, and began writing songs together last year after Zach was told his illness was terminal. The pair have been so prolific over the past few months that they already have a seven-song EP, Fix Me Up, out under the moniker A Firm Handshake.

“‘Clouds’ was one of the first ones he did, so I think it really inspired him to write more,” Brown says. “I mean, when you have people from around the world commenting on a video, ‘Zach, we love you! Prayers from Poland!’ That kind of thing, it’s incredible, and I think it keeps him hopeful. It keeps me hopeful.”

Brown says she’s been blown away by the response Sobiech’s music has received. She’s been by Sobiech’s side as he’s had the opportunity to appear on CNN, star in high-production music videos, fly out to New York to be signed to publishing and royalties powerhouse BMI, and perform in front of a sold-out crowd at the Varsity Theater.

“It’s really, really cool. Like, I’ll be called from my Econ class from the principal’s office, and I’ll go there and they have like a package from Japan of letters for Zach, or like a postcard from Thailand from a boy who is learning guitar because he heard Zach’s song,” she says. “It’s just really, really cool that it’s making a difference all around the world.”

“I think it’s a combination of who he is -- he’s just this very bright light, and kind of a classic tragedy almost, that people can relate to, but it’s real life,” says Zach’s uncle, Luke Friedrich, who is also a musician himself. “He’s this young kid who’s easy to identify with, and he’s going to die, and he wrote this beautiful song that totally captures it in this beautiful way. He does what any musician really tries to do with a song. Here’s a piece of, a view of something beautiful, and the imagery, he just captured it perfectly, and people just love it. And it’s catchy and it’s a good song, a perfect pop formula, and there’s real meaning behind it, there’s no BS, it’s just totally, 100% genuine. It’s just ridiculous. How can anyone not like it?”

Friedrich, who plays in the local bands Crimes and Squares, says he immediately recognized the potential in Zach’s songwriting abilities. He’s one of the countless family members, friends, and fans who are left wondering what Zach Sobiech’s music career could have become if—like the lyrics of his hit song ask—he had a little more time.

“The first time I ever heard a song that he wrote was the Clouds song, my sister Laura, his mother, sent it to me on my phone, and it was just an acoustic version of it—I heard it, and it just blew me away. I wasn’t expecting a whole lot. It took me a long time to write a song that was any good at all, and he was just turning 16 at the time, maybe still only 15, so to hear that song was just amazing. Everyone that I played it for—like, really cynical music types who hate most everything—was in love with this song. The raw track, the raw acoustic version is still by far my favorite.”

Zach Sobiech passed away today, just three weeks after his 18th birthday. To date, over $100,000 has been raised for the Chidren’s Cancer Research Zach Sobiech Ostersarcoma Fund, and "Clouds" has been downloaded over 30,000 times.

Thanks to his music, Zach’s legacy will live on forever.