How the hell did this happen?

A highly odd and irregular feeling has grasped me lately. I don't know what to think of it. It's almost too much to even think about, but lately I've started having the urge to run. I don't know what's come over me. I am nothing if not a very low-energy couch and computer chair potato, and yet, here I find myself with the urge to run. I not only ran a short distance from my car to work this morning, but I ran nearly the whole way back to my car this afternoon. I fear something is terribly wrong with me. This is terribly peculiar.