My arm muscles are sore, strangely, because of lifting books. What a geek's life huh? I was at the Philippine Star library again yesterday (and I'll be there tomorrow again as well), lifting huge books that compiled all the newspaper articles of 1987. And yes, they are heavy. If this keeps up, lifting them will be the equivalent of me going to the gym.
My legs and foot are in similar pain, not because of all the jogging I'm doing, but probably because I've been using my legs as a table for the books. One of the bones in my foot also seems to be sore (but not swelling), which is why it's a bit difficult for me to walk, much less run (but I've done so).