He is stating that the matter is more deeper than bodies, more soulful and more what matters on the inside with our souls. "Gorvern your own bodies" referring to not an actual body and its organs but what is inside a body deeply soulfully.
B. Bone denesity because as we age our bones become brittle and can break easily hence why older people often break their wrist or hips when falling. And being fit can help.
