We have to make strenuous efforts when we first try to return to where we fell from. For we resent abandoning our own desires, and we think that we can carry out both God’s wishes and our own – which is impossible. Our Lord Himself said, ‘I have come to do, not My own will, but the will of the Father who sent Me’ (cf. John 6:38), even though the will of Father, Son and Holy Spirit is one, since they constitute a single inseparable nature. But He said this on our account and with respect to the will of the flesh. For if the flesh is not consumed and if a man is not wholly led by the Spirit of God, he will not do the will of God unless he is forced to. But when the grace of the Spirit rules within him, then he no longer has a will of his own, but whatever he does is according to God’s will. Then he is at peace. Men like that will be called sons of God (cf. Matt. 5:9), because they will the will of their Father, as did the Son of God who is also God.
St. Peter of Damaskos, Philokalia, Volume 3, p. 84.