Lethargy

Yesterday I had a migraine and I'm feeling a little out of it today. It is very rare that I have so little energy. What does it mean to feel out of energy? I seem to be able to type and to get non-physical work done. And actually, now that I think of it, I did ride my bike to work today, so I'm getting physical work done too. So I guess it's just a feeling. Jorge Aigla (my karate teacher from college) says, "Pain is a sensation. It is not an emotion." Maybe lethargy is just a feeling not reflected in outward-facing reality. But then again, other people can probably see it in my face.