When you study the Book of Job, you will observe a vivid demonstration of the difference between the work of God and the work of the devil. All the atrocities and all the afflictions and problems that Job went through were the devil's operations through natural causes. 
Sickness is not an act of God. God doesn't teach you anything with sickness. So when the Bible says, “Thy will be done…,” it includes your spirit, your soul, your body, your family, your finances and your affairs. Every aspect of your life should be a reflection of the will of God. That is, if you are a child of God, the totality of your life should be the will of God in motion.
Just like Jesus said, “He who has seen Me has seen the Father (John 14:9).” You should be able to say that he that has seen you has seen the will of God. The will of God is not for you to be sick, poor or struggling through life without enough to eat and to take care of your legitimate responsibilities. If that is your current experience, understand that it is the devil trying to impose his negative will on you; but through the instrumentality of prayer, you can resist it and enforce the will of God in your own case. 
Confess these words: The word of God is the will of God for me. When I have the word of God, I know the will of God and I'm going to have the will of God established in my life. I'm not going to say amen to what the devil is doing any more from today, in Jesus’ name. Amen!
BIBLE IN A YEAR: Numbers 10:1-11:23, Mark 14:1-21, Psalm 51:1-19, Proverbs 10:31-32