I know, I know, Stephen Covey is so 1989. Covey-esque buzzwords ("Sharpen the saw" anyone?) have become ubiquitous enough to have lost some of their initial punch. But, there's a reason he gave rise to an entire industry and remains one of the most respected people in management psychology to this day. His reaction against shallow behavioral change and advocacy of deep personal commitment to timeless principles remains a powerful and vibrant message. Go ahead, shut your door, and see what the old guy has to say, I won't tell.