Robin Greenfield once dreamed of becoming a millionaire by 30. Now, at 36, he voluntarily lives on less than $11,000 per year, eats mostly foraged and locally grown food and lives in a small dwelling that he built himself. He's part of a larger movement of "zero-waste activism," which includes those who strive to eliminate trash altogether, as well as people who maintain a more typical lifestyle but limit the amount they consume. For Greenfield, it's meant changing nearly every aspect of his lifestyle.