The thesaurus might equate “disabled” with synonyms like “useless” and “mutilated,” but groundbreaking runner, actor and activist Aimee Mullins is out to redefine the word. Speaking at TEDMED, she hows how adversity — in her case, being born without shinbones — actually opens the door for human potential. (Recorded at TEDMED, November 2009, in San Diego, CA. Duration: 21:58)