In life and work, we have a hard time changing course. When we wind up in a miserable job, a failing project, or a floundering romantic relationship, we rationalize, make excuses, and stick with our bad decisions—even when the writing's on the wall. Why? Usually we assume the driving force is sunk costs: we don't want to admit we've wasted that time or money. But in fact, the root of our stubbornness is a psychological trap called “escalation of commitment.” Once we understand that, we can start taking steps to protect ourselves from… well, ourselves.