Not Sure Why

I'm having a little depression issue today. It's not too bad, but what bugs me is I have no idea WHY I feel this way. It's just one of those "down-for-no-reason" days. Those annoy me. If I'm going to feel bad, I at least like to know WHY I feel bad. At least then I won't look like an idiot when someone says, "What's wrong?" and I have to say "I dunno". Of course, it's not an "I-can't-get-out-of-bed" day, which I'm thankful for. Just don't know why I keep having fleeting moments of sadness. Just one of those days, I guess. This, too, shall pass.