I also have thyroid disease, one of the symptoms is that bones and muscles are weaker, and that losing lean mass is very easy, I tried running before, but it weakens me (literally, I lose muscle), also it hurts a lot (I feel a burning sensation in my leg bones when I run long distances, or when I run several days in a row).<p>The only exercises I do that actually help my health is weight lifting with low reps (with high reps I also start to lose muscle).