when you're doing fine work or whatever else requires a good deal of focus, you may still want to pay attention to stuff that you're actually doing aside from whatever you're focusing on. trust me...
an explanation if you'd like. bare with this, it's kinda long but i'll try to make it interesting.
i recently managed to chip my front teeth. i didn't do this from falling down the stairs. nor walking into a door or even finding a chunk of bone in my hamburger. oh no. i was eating a muffin. the muffin was of no particularly dangerous variety. probably banana nut. the nuts were properly shelled.
i managed to chip these front teeth by chewing with an underbite. instead of taking the bite such that the lower teeth fit snugly behind the upper, i somehow stuck out my jaw in biting down brought it back thereby chipping a good chunk off of the top tooth with the bottom. the bottom's just a bit shorter now as well. at the time i chalked it up to mine being an idiot but i think there's a more specific cause.
i noticed that while i'm drilling out small bits, chisseling tiny portions off of styrene or otherwise doing some fine work, i stick out my jaw. now since i'm obsessive i'll sit there like that looking like a cross-eyed bulldog with my tongue sticking out the side for some 2 hours at a time drilling miniscule holes in track link hinges. of course, afterwards i'll underbite for 3 days and yes i'll constantly end up gritting my front teeth like i'm trying to make a flint knife out of my inscisors. it's usually not nearly as bad as that one muffin incident but still very irritating.
the point: like i said, pay attention to what you're actually doing if you're focusing on something specific. not only will you save yourself looking stupid without knowing it, you might actually save yourself the dentist's visit.
and watch out for those muffins.