"And hope maketh not ashamed; because the love of God is shed abroad in our hearts by the Holy Ghost which is given unto us."
Romans 5:5
One way for us to stay healthy, spirit, soul and body is to walk in love.
God gave His laws and commandment to His people to prove to them that they needed a Savior.
Galatians 3:24 says the served as a schoolmaster to bring His people to Jesus. They needed a redeemer.
Are we able to obey Jesus' commandment to "love one another" [John 13:34] any better than the Old Testament people were able to keep the Law? The people under the Law had no power to keep it. But we who are under the New Testament, who are born-again with the Holy Spirit indwelling us have the love of God in our spirits to give us the power to keep the law of love. And as long as we walk in love, we have the power to fulfill the other commandments also.
Our purpose on this earth is to walk in love. And as long was we walk in love and obedience, our God will take sickness from us when we ask.