We’ve all heard a great deal about the power of positive thinking. Organizations encourage it among their employees in an effort to boost performance and engagement, and it’s a key tenet of “managing yourself” well; affirmative messages about perseverance, resilience, and vision adorn many an office wall. In the wake of the Great Recession, some businesses even hired happiness coaches to get their workers looking on the bright side. And an optimistic attitude is expected of leaders; politicians and corporate executives should always have that “think it-do it” spirit on display.