I wasn't feeling the somber. I just wasn't.
But I _was_ feeling like many things I'd done recently were in one of two tone-centers about a tritone apart, so I picked a key in the middle... and like I had done some things in major modes recently, so I picked a flavor of minor. I arrived at the tempo artificially as well; it's (2^(1/2))*60 [yesterday's tempo] ~ 85bpm.
My aims were to not make it too sad (even for being in minor) and not to make it too high-energy and dramatic. To chill a bit.
But the tempo, key center, and mode affected me the way they did. So although it's an absolutely gorgeous Spring day outside, this slightly sad song got sung, nonetheless. There it is.