I too sew standing up. I didn't years ago, but after surgery left me with a spine/rib issue resulting in severe scoliosis, I lost 4 inches in height. Now, at only 5'2", I have a harder to seeing my work if I sit and sew, no to mention because I sew at a kitchen table, I have to lift my arms and this causes me additional shoulder, neck and upper-back pain, of which my surgery left me with plenty of already. By standing I have a great viewing angle, and my arms are in a downward reaching position, which causes less strain on my shoulders. I've tried using an elevating office chair, but find myself standing and sewing after ironing or such. Plus, I'm sure it burns a lot more calories to stand, much healthier than sitting for long periods.