On Christmas night, Ben Breedlove, a bright and engaging 18-year-old, died from complications of hypertrophic cardiomyopathy (HCM), an abnormal thickening of the heart's walls. He had already outlived his life expectancy with the hereditary condition. And while his story is heartbreaking, Breedlove has already left a legacy of warmth and hope that outshines the tragedy of his death: a video the Austin, Texas teen left behind has gone viral on YouTube, touching thousands of people who had never met him, and bringing one famous rapper to tears. For more than a year, Breedlove had developed a devoted following on YouTube. Charming and witty, Breedlove would offer kids his age from all over the world advice on everything from dating to studying. But the video he made just before Christmas was of a much more personal and intimate nature. He shared the details of living and often struggling with a disease that was supposed to have taken his life years earlier. He does so wordlessly, his message written on a series of index cards, as an instrumental version of Gary Jules's Mad World played in the background.