I’m a pretty happy guy, but around the middle of the week I got hit by a several days of sadness that seemed to be triggered by nothing in particular, and about nothing in particular. But it was strong and very sad. Usually I’m able to quickly nip in the bud things that pull me down… I make my co-workers (and myself) laugh by cursing my computer as a "stupid piece of electronic excrement" when something doesn’t go as expected.
But this was kind of like the dementors of Harry Potter (though thankfully, on a much less intense scale)… joy just seemed to be taken away, and replaced with nothing at all. Now, it’s back, and I’m very glad. Funny how you don’t really appreciate what you have till you don’t.