Start with the chair
Set up from the floor upward, because each adjustment depends on the one below it. Raise or lower the seat until your feet rest flat and your thighs are about level, with the hips even with the knees or slightly above them. Leave a gap of two or three fingers between the front of the seat and the back of your knees. Sit back so that the chair supports the curve of your lower back, and if it has no lumbar support, a rolled towel does the job. When the desk height forces the chair up, add a footrest or a ream of paper under your feet.
Screen, keys and mouse
Place the monitor about an arm's length away. If you wear bifocals or progressive lenses, lower the screen a few inches so you are not tipping your head back to read. Keep the keyboard close enough that your upper arms hang relaxed at your sides. Wrists should stay straight and should float while you type, since planting them on the desk edge compresses the underside of the wrist. Keep the mouse right beside the keyboard, because reaching for it all day is a common source of shoulder pain.
A laptop on a desk cannot be correct for the neck and the hands at once, as the screen and keys are joined. Raise it on a stand or a stack of books and add an external keyboard and mouse, which fixes the whole problem for under fifty dollars.
Standing desks and movement
Standing all day is not the cure; it trades back complaints for foot and leg ones. Set a standing desk at elbow height, alternate every thirty to sixty minutes, and use a cushioned mat. No posture is good for hours, and the best one is the next one. Three moves undo most of what sitting does: chin tucks, a chest stretch in a doorway held for thirty seconds, and a kneeling hip flexor stretch on each side.
When it is more than stiffness
Numbness or tingling in the hands, pain that travels down an arm or a leg, pain that wakes you at night, or an ache that lasts more than two weeks despite changes should go to a doctor or physical therapist.
Tip Hold your phone up near eye level instead of dropping your head to it, since a head tilted far forward multiplies the load on the neck several times over.
