Just a reminder to unclench your teeth and relax your cheeks once in a while.
It's a fantastic release of tension if you just exhale out while relaxing your cheeks. Try it! Something I learned in EST training, amazingly enough.
It's amazing how much tension we hold in our cheeks and jaws, as well as the neck and shoulders. Here's a great, if a bit technical, series of neck and shoulder stretches:
http://www.nismat.org/orthocor/progr...ck/neckex.html