Zach Sobiech got diagnosed with terminal cancer at the age of 14. He celebrated his 18th birthday on May 3, and was told by doctors last June that he had possibly less than a year to live. That December, he released “Clouds.” The song about facing death got more than three million YouTube views. He passed away last week, but not before leaving the world with an incredible legacy. “It’s really simple, actually,” Zach says of learning to make the world a better place: “Just try to make people happy.” Watch the moving video of his last days here.