A good rule with FOP is to do what feels comfortable. If moving a certain way or sitting in a certain position hurts, your body is telling you that it's not good for you to do it. One thing that can help with FOP is to take good care of your teeth. Try not to get any cavities. You should brush and floss your teeth every day.
Some people brush after every meal.
Don't eat sweets, sticky foods, or soda in between meals because the sugar sticks to your teeth and cause cavities. If you do snack on something sweet, brush your teeth as soon as you're done eating. There are plaque rinses to keep your teeth clean and fluoride treatments to make them strong. Ask your dentist about the best way to take care of your teeth. Be sure to have a check-up twice a year.