If you have a non-ergonomic chair and you want to make it more comfortable rather than changing it, here are some things you can do. Most ergonomic armless office chairs have some advanced adjustment options that regular chairs don’t have. However, every office chair allows you to adjust the height, which can be vital for your posture. Therefore, it's extremely important you adjust it so that your feet are flat on the floor. Apart from that, you can also get an external lumbar pillow and add a seat cushion. All of these adjustments can significantly improve your overall comfort levels.