If you're reaching for a mouse, this causes you to overextend your arm repeatedly, straining your elbow and shoulder. It also forces you to lean forward, adding stress on the neck, back and hips. If any of your body parts are at an extreme range of motion, that's an awkward reach. You have to recognize those things in your work habits and correct them. Move yourself closer to the item in question, or move the item closer to you.
Warning signs are pain, tingling, numbness or weakness located between the neck and hands.
Your Elbows Use a chair with armrests that support your elbows. To avoid neck strain, keep your monitor at arm's length, with the top of the monitor level with your eyes. Tuck your chin in slightly so that looking at the screen's center is comfortable. Do Avoid Monitor Glare Eyestrain is experienced by more than 30 percent of users working at computers more than four hours a day. Position your monitor so it doesn't reflect any bright light sources, especially from windows.