5 We say in the third petition, “Your will be done as in heaven, so in earth.” What is this? That as the Angels serve You in heaven, so we may serve You in earth. For His holy Angels obey Him; they do not offend Him; they do His commands through the love of Him. This we pray for then, that we too may do the commands of God in love. Again, these words are understood in another way, “Your will be done as in heaven, so in earth.” Heaven in us is the soul, earth in us is the body. What then is, “Your will be done as in heaven, so in earth”? As we hear Your precepts, so may our flesh consent unto us; lest, while flesh and spirit strive together, we be not able to fulfil the commands of God.
Source: Sermons on Selected Lessons of the New Testament (New Advent)