Got a bad case of the Mondays? Yeahhhh.. I'm gonna go ahead and have you take a look at these and cheer up a little then.
We know work can be a drag sometimes, but that isn't because it's crappy (not a guarantee). Instead think of it as a loss of the self. It makes perfect sense. You start the job, you like the job, you're there for however long, you start to get annoyed with the job... what comes next. You find some way to get some more of your "self" back in the workplace.