Thoughts on Being Sick

I don't get sick very often.  I remember being sick a normal amount when I was a kid.  Between the germs getting passed around at school and the germs my mom would bring home from the clinic where she worked, I would get the flu or strep throat fairly regularly.  As an adult, I have rarely caught anything worse than a mild head cold, despite spending most of my working hours surrounded by miniature germ factories.  I have never been paranoid about germs (I HATE that antibacterial hand sanitizer crap), and I honestly think that my willingness to be exposed to them now and again has helped me build up a kick-ass immune system.

That being said, I caught something this past weekend that kicked my butt in a big way.  It had some head cold-y like symptoms; sneezing, runny/stuffy nose, watery eyes, but the worst was the complete exhaustion.  I had to spend a significant amount of time resting to prepare myself for a walk from the bedroom to the living room.  I spent the majority of 4 days doing nothing but lying down.  I barely moved at all, thanks to my darling husband and his excellent nursing skills. 

I'm feeling much better now (Thanks for asking!).  On Monday morning I was able to get up and return to my regular schedule, feeling 100% normal.  This leaves me with one question:

How does my body know the difference between me lying around for 4 days sick and me lying around for 4 days because I'm a lazy bum?  If I had done that much sitting on the couch voluntarily, my joints and lower back would be in an uproar.  If I spend 1 Saturday lounging in front of the TV, my knees complain about it for the rest of the week.  But not a single joint had one word to say about my lack of movement while I was sick.  What's up with that?