Ergonomics

The following information is backed by two-year experience.

You need a footrest (e.g., Kensington SoleSaver Adjustable Footrest), a back cushion, and most importantly, daily exercise (e.g., keep (link here)).

If you are using a laptop, be sure to have a monitor. Ensure your eyes are in the center of the monitor, and your hands are rested comfortably on the keyboard.