One thing that no one talks about in Ergonomics is your eyes. But think about it, how often do you get sore behind the eyes after starring at your computer screen all day. Two things you can control is the distance from the screen you sit at and also the light in your environment. Your screen should be vacant of light reflection and approx arms length away from your body when seated.
Also give your eyes a rest by using you long distance sight once every half hour, looking out a window or the back down the hallway. This will give your eyes a rest and take the strain out of them. Watch this video for more information.