From Inc.com's most popular columnist, a counterintuitive--but highly practical--guide to finding and maintaining the motivation to achieve great things. It's comforting to imagine that superstars in their fields were just born better equipped than the rest of us. When a co-worker loses 20 pounds, or a friend runs a marathon while completing a huge project at work, we assume they have more grit, more willpower, more innate talent, and above all, more motivation to see their goals through. But