You simply cannot stand your boss any longer.
Every employee gets aggravated with his or her boss now and then. But if "now and then" becomes "all the time" in your office, the friction might be justification to move to a new position.
Perhaps you feel that your boss doesn't do his or her job as well as you could. Maybe you don't like the direction he or she insists on leading your team. Or maybe you simply have a fundamental communication issue with your boss that makes every exchange tense and filled with second-guessing and distrust. All of these situations can lead to bitterness and resentment as you complete assigned tasks -- in that situation, do you think your work will be the best it can be, or will it show your disappointment and frustration with your work environment?
If you're facing this situation, think about what truly aggravates you about your boss. If it's a personality quirk or interpersonal issue, is there a way you can watch for this in a future job interview, so that you don't move from one bad situation to another? If it's a matter of leadership or decision-making, can you identify solutions you could present to a new employer, showing that you've got what it takes to be a better leader? Answer these questions before you choose a new job, so that you don't jump hastily from one bad situation into another.