To set up an ergonomic chair, start by adjusting the seat height so that your feet are flat on the floor or a foot rest. Ensure your knees are at a 90-degree angle. Adjust the seat depth to allow a few inches of space between the edge of the seat and the back of your knees. Adjust the back rest to support the natural curve of your spine, and use lumbar support if available. Armrests should be adjusted to allow your arms to rest comfortably, with relaxed shoulders.