One problem with chairs, and many car seats too, is that manufacturers don't know how to design for lumbar support. With the auto seat for instance, the lumbar support is in the correct location when the seat is empty but fails miserably when the weight of the passenger is applied.
This problem was solved when I was given this "whutsit thing ". I have no idea what it's called but it weighs just ounces and feels like it has fine grain sand inside and will conform to any shape, even mine.:biggrin: The contents must be some sort of miniature synthetic styrofoam pellets of some sort. To use it just sit in the chair, grasp each end and while slightly leaning forward raise it over one's head and drop it. It will stop falling in just the right place. Now just lean back and say "AH, that feels so good".