Maybe I'm Turning Into a Butterfly?

I don't get it. I went for a run yesterday for the first time in ages and felt fine. Today, mindful of injury, I did a short session of stretching.

So I'm now at my desk and every muscle seems to be radiating heat.

Maybe it's my fault--I mean, hot yoga's so damn expensive ... So I just exercise in a foil-lined room with an old microwave that I took the back and sides off of.

But seriously, whence cometh this strange affliction?

Ah-maybe that's it:



Or perhaps this is more like it: