Especially when you have battle damage.
I woke up this morning and my neck was sore on the left hand side. By noon, moving it in pretty much any direction, even in the slightest, sent muscle spasms of biblical proportions from my jaw to my lower back.
I had to leave work and go home (and oh, momma... the drive was sweet!).
Now I'm all hopped up on vicodin and life is better (if not somewhat fuzzy).
I guess that's what happens when you have a couple of cars drive over your ass in your youth.