Joyfully obeying God is perhaps the highest form of worship. (1Sa 15:22b) It’s love acting out, “God, You’re worthy; You’re supremely important; Your desire is my only priority.” Those who love Him need not know why He commands, only that He does; “for this is the love of God, that we keep His commandments.” (1Jn 5:3)
The greatest example of obedience ever may be Christ praying in the garden, “Father, if thou be willing, remove this cup from me: nevertheless not my will, but thine, be done.“ (Lk 22:42) As He’d planned from eternity past, His will was to ransom those He loved. Yet He could not be self-willed in dying for us: He was willing to give that up and die an eternal failure in the garden, lying on His face in the dirt, if that was His Father’s will. It was the ultimate submission, where He Himself learned obedience and revealed His perfection. He was then fit to author eternal salvation for all who obey Him. (He 5:7-9)
So often God gives commands without telling us why, yet the quickened soul implicitly knows God is good. Like Christ, the Author and Finisher of our faith, we obey, not always knowing what blessing will come, but that there is blessing in any and all obedience. (He 12:1-2) Yet it is not for blessing we obey, but simply for Him, because He is worthy.
My thoughts on this is that the cup is the cup of salvation, and that Jesus is so concerned about the world and wants so badly for people to be saved, that his soul becomes deadly sorrowful even thinking that there might be a possibility that God may change is plan and that salvation though Jesus might not be offered to the world. Out of this concern for us Jesus is asking God on our behalf to take/remove the cup from him so that it can be given as a gift to the world. Jesus wants the cup of salvation to be given to the world but knows that eternal life is God’s gift to the world (The gift of God is eternal life through Jesus), and as such, it is God who must make this happen, which is why Jesus is asking God to take/remove the cup and let the cup pass from him to the world.
His concern is definitely for us! If His Father doesn’t come through and help Him survive the attack in the Garden, and lets Him die there, no one loses but us!
A likely source of the sorrow is Christ being lead by His Father to begin to deeply experience the godly sorrow of being separated from His Father, and also to experience the Father’s mutual sorrow in being separated from Christ.
If there is any aspect of Christ’s suffering that is intolerable, even for an instant, it is to be separated from fellowship and communion with His Father, as He is being treated like a rebel and an enemy on account of our sin.
Perhaps this sorrow is so intense that even Christ Himself is unable to bear it in His physical body for very long and needs supernatural help just to endure it. And perhaps it is this same sorrow that eventually kills Christ so quickly on the cross. (“And Pilate marveled if he were already dead: and calling unto him the centurion, he asked him whether he had been any while dead.” Mk 15:44)