In all of my reading, I have not noticed any
negative effects coming from combining
exercise with a definitive diagnosis of MS. In fact, according to friends I have who have MS, they live productive, normal lives. Don't let MS stop you. In fac,t the exercise should be good in keeping your motor function, etc.
MS is something you'll have to deal with, of course, but don't let it define who you are. Best of luck you you in your journey.