At design school, one of my professors said that Frank Lloyd Wright tried not to sketch until his brain was absolutely filled with ideas and he had to get it all out on paper. Other designers I've met need to start sketching idly, finding that ideas then present themselves on the page. For creatives, the question of where ideas come from is one that could be asked, and answered, for ages, and the variety of answers would never be boring.
National-Endowment-for-the-Arts-backed Transom, an organization dedicated to telling the stories of creatives, has put together a video where they asked a variety of folks (including artist Chuck Close, author Susan Orlean, pro skateboarder Ray Barbee, filmmaker David Lynch and others) "Where do ideas come from?" From Close stating that "Inspiration is for amateurs, the rest of us just show up and get to work" to Barbee citing that "Mimicking can lead to originality," their answers are as diverse as their bodies of work: