There were a few times in my life when Sunday nights brought that awful pit-in-the-stomach feeling of dread thinking about the approaching Monday morning. This occurred most frequently during my school years and for about four months when I worked for a health insurance giant that shall remain nameless because if I speak its name I get nauseous.
I look back and see that the feeling of dread occurred because of what awaited me, e.g., Monday morning French class, a long bus ride, or, in the case of the insurance company, eight hours of mind-numbing, soul-anesthetizing boredom. School stuff is easy enough to deal with because you know there's an end in sight. But dreading your job for days on end can seriously depress you.
There are career-oriented self-help books out there that tell you to "find your passion" when choosing your career. I agree wholeheartedly with this statement if you're just starting out or if you are at a serious crossroads in your life. Sit down, brush all thoughts of practicality out of your mind for a minute, and think of the one thing (keep it clean) that persistently holds your interest. Is there any way you can make a career out of it?
Most people postpone, or defer entirely, "finding their passion" because the're busy "finding money to pay the bills." In other words, if you have a family of six to support, you'd better take a second look at your passion if it happens to be playing hip hop music on the calliope. [I just made that up so if there is really such a music genre, I'd rather not know about it.]
But seriously, you spend at least a third of your life at work. If you are merely suffering through those hours to get to what you really want to do, then you owe it to yourself to try to find something that you're more passionate about.