Faith + Reason = Truth

People live in fear.  Fear of bad traffic, bad weather, dying, getting sick, losing jobs - quite a pervasive emotion.  The job thing baffles me though.  It didn't ALWAYS baffle me - I also used to fear making a mistake at my prior stints as a financial analyst, or missing a deadline, or saying the wrong thing in the meeting, thinking it would get me fired.  It wouldn't have.  Does Steve Nash fear making a bad pass and throwing the ball away?  Does Dirk Nowitzki fear missing the tying shot as the ball leaves his hand with time expiring?  Maybe.  But they don't fear losing their jobs.  If you're good, and if the people in charge know you're giving a solid, honest effort, that's really all that matters.  When you mess up, find out how or why, then let them know it mattered enough to you to look into how it happened so that it can be (hopefully) avoided in the future.  Realize that you don't have all the answers, and focus on what you believe you need to be able to do at your job.
And if the REAL reason you fear losing your job is because you're slacking or daydreaming or, for whatever reason, desperately longing to be anyplace other than your job, then you don't belong there anyway and they'll be doing you a favor by firing you since you're obviously too wussy to stop wasting your precious life and leave on your own.