I made a cover for my heating pad that will keep it on my shoulders ( which would warm you), or put it on your lap, or get a small space heater - they run as inexpensive as $20. Just be sure it's not up against anything and get the kind that shuts off if it's tipped over. Put a quilt over your lap as you sew. I find that my overhead lights generate heat, as does my iron. Certainly not enough to warm a room, but I have been known to press fabric just to warm up my hands!