When you go to work, what's the prevailing question in your mind? Is it "What kind of fiasco will I have to deal with today?" or "I wonder if I can accomplish [your goal here] today?"
Do you have a sense of impending doom or triumph?
A sense of impending doom is not sustainable. You'll burn out long before you can make any lasting contribution. Make this the last day you go to work feeling pessimistic. Spend 15 minutes identifying what, or who, is maintaining the dark cloud over your head.
If it's a person who hasn't been properly managed, abandon your old style and apply one that works. If it's someone who refuses to be managed, terminate them. Nobody should have that kind of power over you.
If the person is above you on the ladder, it's time for a heart-to-heart or a new job. Impending doom is not sustainable. Become an empowered manager today, even if it means empowering yourself.
If the cloud of doom is being maintained by something you haven't conquered yet---high blood sample rejection rates, crippling staff turnover, rampant inter- or intradepartmental friction, or a Systemic Staff Disorder (SSD) such as gossip, low morale, apathy, non-compliance with policies/procedures---put it on project status. Start obliterating the obstacles that keep the cloud from dissipating. Tomorrow is too late.
If you start your day with a sense of impending triumph, good for you. You are blessed beyond words. Now go out and find someone with a sense of impending doom and show them how to get where you are.