Gary Vaynerchuk, the serial entrepreneur, best-selling author and public speaker, has built his VaynerMedia empire on straight talk and savvy sales instincts, but reveals he didn't always use his "superpower" in the most effective way. In an interview with Fortune for Champion Mindset, Vaynerchuk revealed his biggest professional regret: not practicing enough "candor" in managing his employees during the early years of his career.