Summary
Highlights
Adjust your chair height so elbows are bent at 90 degrees. If your feet don't touch the floor, use a footstool or a ream of paper.
Position your monitor at arm's length, with the top of the screen at eye level. Use reams of paper if your monitor isn't adjustable. For two monitors, place the primary one directly in front, or center yourself between two equally used monitors. For laptops, use a kickstand and external keyboard/mouse.
Place your keyboard where your hands naturally rest, and your mouse next to it. Move from your elbow, not your shoulder, to prevent strain. Avoid reaching for your tools.
Place your phone on your non-writing side to avoid cradling it with your shoulder, which can lead to neck pain. If you use your phone frequently, consider a headset to keep your hands free.
Prevent slouching by performing exercises while sitting, such as chin tucks, upper trap stretches, scapular retractions, and pelvic tilts. Most importantly, get up and walk around every hour.