when you feel like you're at your lowest point, imagine you're like a ball that will bounce as soon as it hits the floor. or maybe like the rebound concept. the more tense the stroke is, the higher the rebound is. and when you let the stick do the work, thus you'll find lesser stress on the arms.
sorry for being such a dummy, nothing i can help. but if you need anything else to lessen the stress, then my arms are available for a free hug ;)