You might want to go over the ergonomics of your sewing area.
I once took a quilting class by Harriet Hargrave and she spent quite a while at the beginning of the 2 day class on proper ergonomics. I was so impressed that when I got home I reviewed my sewing area. I went to a good office furniture store and luckily found the Herman Miller airlon [?spelling] chair didn't feel good with my body. I ended up getting a funny stool that is height adjustable and feels like I am sitting on a balance ball ... it almost forces me to sit properly. Well worth the cost.
alice