We know the person who has a healthy heart is usually in rather good shape physically.
I believe this goes further than the physical and is speaking of a heart in tune with God. One of the main things mentioned in Romans 10:9-10 to be saved is to believe in the heart.
Envy and strife go hand in hand. Envy eats you up from within and will totally destroy you.
“The rottenness of the bones” speaks of suffering which is like a painful and incurable condition.
Under Gods command 