A good TV watching or dining chair doesn't always make for a good work chair. "The best chair will be an individual decision," St. John explained, "but it should allow you to sit up straight with your weight centred on your sit bones rather than rolling the tailbone under, slumping the lower back into a rounded position, and sending the head forward." Find an office chair that works best for you and encourages upright posture. "Some people like lower back support to remind them to sit up straight, while others find it encourages collapsing into it," St. John said — so, it's really a personal call.