Psalm 73:26 (NASB)
My flesh and my heart may fail, But God is the strength of my heart and my portion forever.
A saint in fellowship with God will not be deterred by what the devil throws at him. That's because a saint is resolute and steadfast in one's confidence and faith in the Lord. Nothing that Satan can afflict a saint with, including sickness and disease, can rob a saint's eternal victory.