When quilting with a domestic/home machine, its important not to hunch your shoulders up and just relax your body. If possible have your machine down in a table so that it sits flat, much easier on your shoulders,neck and back. Have your chair at the correct height. I only quilt for 1/2 hour at a time and go do something else that requires different muscles. Leah Day has great youtube videos on machine quilting with a regular machine.
Sharon