19 “I cannot of myself do anything: as I hear, I judge: and my judgment is just.” Else we might have said to Him, “You will judge, and the Father will not judge, for 'all judgment has He given to the Son.' it is not, therefore, according to the Father that You will judge.” Hence He added, “I cannot of myself do anything: as I hear, I judge: and my judgment is just; because I seek not my own will, but the will of Him that sent me.” Undoubtedly the Son quickens whom He will. He seeks not His own will, but the will of Him that sent Him. Not my own, my proper will; not mine, not the Son of man's; not mine to resist God. For men do their own will, not God's, when they do what they list, not what God commands; but when they do what they list, so as yet to follow God's will, they do not their own will, notwithstanding they do what they list to do. Do what you are bidden willingly, and thus shall you both do what you will, and also not do your own will, but His that bids.
Source: Tractates on the Gospel of John (New Advent)