Me too - I used to hurt all over. You're moving a lot of fabric and you're trying to coordinate a lot of activity at once, so you get tense and forget to breathe.
Keep the quilt supported so that it's not falling off the table and dragging against your efforts. I have a table behind my machine and another to my left that hold the quilt "puddled" in big folds. I keep about a square foot nearest the needle flat and smooth, but I let the rest of the quilt sit where it wants to.
Make the quilting area around the needle as slippery as you can to cut down on drag, too. Use some rubber/nitrile gloves with the thumb and pointer finger cut out so that you can get some real traction on the quilt.
All of those things cut the effort required to move the quilt. Stop and shake out your elbows and wrists and stretch your neck and shoulders every now and then. :)