This is one example of an ergonomically correct workstation. Some people would be more comfortable with slight adjustments such as tilting the keyboard up a bit or removing the armrests from the chair, but this picture shows many of the important pieces of a good workstation.
Sitting with the ears directly above the shoulders, which in turn are over the hips, helps prevent back strain. Placing a lumbar pillow or roll against the small of the back provides additional support.
WebMD Medical Reference from Healthwise