An exercise ball! Maybe it's called a "yoga ball" too? I say this as a person that has used a ~$400 chair with mesh on the seat and back. I've had several bou

An exercise ball! Maybe it's called a "yoga ball" too? I say this as a person that has used a ~$400 chair with mesh on the seat and back. I've had several bouts of sciatica over the last few years, even with a moderately soft chair. A registered massage therapist recommended an "exercise ball" and I got a Trideer brand from Amazon. It makes for more small movement, and less/no soreness at the end of the day.