I, too, have arthritis. All the above are great. Though the use of a TENS unit should be evaluated first by a licensed physical therapist and approved by a doctor. When sewing at my machine I do get up more often that I ever used to to just walk a bit and stretch.
When doing hand work I have a quilting/sewing pillow I use so that I don't have to look down so far. I also use it for reading heavy books.
I made some for friends. Just take two 18" squares, RST, and sew together with the corners of the top one at the midline of each side of the other square. Leave an opening and stuff the inside with pillow stuffing. Sew up open seam area. I put small triangular pockets on two opposing sides to hold things that might be wanted.