He was given months to live last June, but that didn’t stop Zach Sobiech from becoming a rock star – and an inspiration to millions.

Sobiech passed away Monday, 17 days after his 18th birthday. First diagnosed with osteosarcoma when he was 14, Sobiech’s music became his way of expressing himself. His song “Clouds” not only went viral last December, but also resulted in a star-studded celebrity tribute video earlier this month.

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“My closure is being able to get my feelings into these songs. So [friends and family] could have something to remember me by, or lean on when I was gone,” he says in a 22-minute film about his story, My Last Days: Meet Zach Sobiech, featured on SoulPancake.

From moments in the hospital, to getting the car of his dreams for a week and dancing with his girlfriend Amy in the living room or the middle of the Minnesota Vikings stadium, each minute is more moving than the last.

Even Justin Baldoni, the documentary’s director, says, “I was not expecting to meet a 17-year-old who would change my life.”

Members of the Sobiech family – parents Rob and Laura, and siblings Alli, Sam and Grace – ask that donations in Zach’s memory go to the Zach Sobiech Osteosarcoma Fund to help carry on Zach’s mission to help kids with cancer.