“Rejoice in the Lord always: And again I say, Rejoice!” (Phil 4:4)
“Be glad in the Lord and rejoice.” (Psalm 32:11).
“A joyful heart is good medicine.” (Proverbs 17:22).
A grateful heart = a joyful heart.
A joyful heart = good medicine.
Good medicine = good health.
Therefore: I will maintain a grateful heart so that it will help me stay healthy.