If you work at a desk or computer, be sure the armrests on your chair are not so long that they prevent you from moving in close to your work. Adjustable armrests can help you find a position that is at the right height and width to support your forearms comfortably. The seat of your chair should be comfortably padded and flat or slightly contoured. It should support the even distribution of your weight over your thighs and back with your feet resting comfortably on the floor. If the seatpan is too soft or deeply contoured, it will be harder for you to change your position.
Movement is important while sitting.
The seat should be wide enough that you can shift slightly from side to side and long enough to support your thighs. You should be able to fit your fist between the front edge of the chair and the back of your bent leg. The front edge of the chair should curve downward so that it does not press into the back of your legs. If you will be using your chair for a variety of tasks or sharing it with others, the seatpan should be height adjustable . The ability to tilt your seatpad forward is a nice option for people who perform sitting tasks or to take pressure off your lower back.