Exodus 15:26

He tested them, saying, “If you will diligently listen and pay attention to the voice of the Lord your God, and do what is right in His sight, and listen to His commandments, and keep (foremost in your thoughts and actively obey) all His precepts and statues, the I will not put on you any of the diseases which I have put on the Egyptians; for I am the Lord who heals you.  

Our spirits should lead our minds and thoughts as we diligently pay attention to the voice of the Lord.  If we stray off with ungodly ideas, our minds become more carnal, and it is harder for healing to come. God keeps telling us that where we focus our thoughts is essential.  Healing is ours when we turn our focus to God and believe in Him.