I agree with what Ruth stated. Baker NT Commentary (Hendriksen, William, and Simon J. Kistemaker) adds some helpful material here as well (though):

He addresses the Object of his prayer in the most intimate manner, saying, “My Father.” We should not separate vs 39 from 42 (see below). Luke 22:43 relates that there came “an angel from heaven to strengthen him.” This may well be considered an answer to his prayer, for though the cup was not taken away, he was given strength to take it to his mouth and drink it until it was empty. The same evangelist in the next verse also states that “being in agony he prayed more earnestly; and his sweat became like great drops of blood falling down upon the ground.”

Jesus now prays that it may be spared him, that is, that it may pass him by. The completely sinless, in fact exemplary nature of the prayer appears from the fact that the main clause “Let this cup be spared me,” is introduced by the subordinate clause, “if it is possible,” which, in turn, is elucidated by the words, “nevertheless, not as I will but as thou wilt.” Jesus is submitting himself entirely to the will of his Father.

Never shall we, who do not even know how our own soul and body interact, be able to grasp how the human nature of Christ, in these solemn moments, related itself toward the divine, or vice versa. To the intense suffering, experienced in Christ’s human nature, was given infinite value by means of the union of this human to the divine nature, within the second person of the Holy Trinity. Therefore his suffering, from first to last, was all-sufficient, that is, sufficient for the sin of the whole world.

Again Jesus retires to the place of solitude. From his sleepy disciples he could expect no help. Again he prays. Though both prayers—the one of verse 39 and that of verse 42—are the same in essence, there is a difference in emphasis. The main clause is no longer, “Let this cup be spared me,” but “Thy will be done,” a petition identical in wording and meaning with the one Jesus had himself taught his disciples (Matt. 6:10b). What is happening, then, is that by his own very painful and distressing experience Jesus is “learning” what it means to be obedient, and is revealing this obedience in a progressively glorious manner.

Reformed and Always Reforming,