Start with your eyes

The top of the screen should sit at eye level. Most neck pain from desk work comes from a laptop screen that sits a hand lower than that, so the head drifts forward and the small muscles at the base of the skull hold it there for eight hours. Two hardback books under the laptop and a cheap external keyboard fix that for most people.

Then your elbows

With the shoulders relaxed, the elbows should rest at about ninety degrees and the forearms should be supported, on the desk or on the chair arms. Reaching forward to a keyboard turns the upper back into a shelf. If the desk is too high, raise the chair and put something under your feet.

The habit that beats the chair

No posture is good for an hour. Set a timer for forty minutes and stand up when it goes, even for thirty seconds. The spine likes variety more than it likes any single position, and the patients who stop coming back are the ones who built that break into the day.