An excerpt from my book Purpose of Prayer .

As we pray for God’s name to be hallowed, and for His kingdom to come, with the same breath we should pray also for His will to be done.  For the holiness of God and the kingdom of God is established by the will of God.

Here we are praying that God would do His good will to overcome what is sinful and evil in the world, that He would do whatever He wishes to do, so that the earth would be as heaven.  And since He wishes that all would be saved, and thus be conformed to His image, this prayer is really a prayer for the salvation and sanctification of all those in the world.

Now, since God has given all men and women a choice, we know that many will choose not to be saved and to go against God’s will.  For that reason I think the aim of this petition is to change the will of man.  Hence, let us pray here that our will would be conformed to His will, that we would willingly, obediently, and cheerfully do His will as it is done by the angels in heaven (Ps. 103:20, 21).  Moreover, because of our tendency to disobedience and laziness, we should pray here that God will make us desire and love His will (which includes everything in the Bible), that we would say with David, “I desire to do Your will, O my God; your law is within my heart” (Ps. 40:8).  Let us also pray that we would be like Job, who said, “I have treasured the word of His mouth more than my daily bread” (Job 23:12).