From: Mark 10:32-45
Third Prophecy of the Passion
 And they (the disciples) were on the road, going up to Jerusalem, and Jesus was walking ahead of them; and they were amazed, and those who followed were afraid. And taking the Twelve again, He began to tell them what was to happen to Him,  saying, "Behold, we are goingup to Jerusalem; and the Son of Man will be delivered to the chief priests and the scribes, and they will condemn Him to death, and deliver Him to the Gentiles;  and they will mock Him, and spit upon Him, and scourge Him, and kill Him; and after three days He will rise."
The Sons of Zebedee Make Their Request
 And James and John, the sons of Zebedee, came forward to Him, and said to Him, "Teacher, we want You to do for us whatever we ask of You."  And He said to them, "What do you want Me to do for you?"  And they said to Him, "Grant us to sit, one at your right hand and one at your left, in your glory."  But Jesus said to them, "You do not know what you are asking. Are you able to drink the cup that I drink, or to be baptized with the baptism with which I am baptized?"  And they said to Him, "We are able." And Jesus said to them, "The cup that I drink you will drink; and with the baptism with which I am baptized, you will be baptized;  but to sit at My right hand or at My left is not Mine to grant, but it is for those for whom it has been prepared."  And when the ten heard it, they began to be indignant at James and John.  And Jesus called them to Him and said to them, "You know that those who are supposed to rule over the Gentiles lord it over them, and their great men exercise authority over them.  But it shall not be so among you; but whoever would be great among you must be your servant,  and whoever would be first among you must be slave of all.  For the Son of Man also came not to be served but to serve, and to give His life as a ransom of many."
32. Jesus was making His way to Jerusalem with a burning desire to see fulfilled everything that He had foretold about His passion and death. He had already told His disciples that He would suffer there, which is why they cannot understand His eagerness. By His own example He is teaching us to carry the cross gladly, not to try to avoid it.
35-44. We can admire the Apostles' humility: they do not disguise their earlier weakness and shortcomings from the first Christians. God also has wanted the Holy Gospel to record the earlier weaknesses of those who will become the unshakeable pillars of the Church. The grace of God works wonders in people's souls: so we should never be pessimistic in the face of our own wretchedness: "I can do all things in Him who strengthens me" (Philippians 4:13).
38. When we ask for anything in prayer, we should be ready, always, to accept God's will, even if it does not coincide with our own: "His Majesty knows best what is suitable for us; it is not for us to advise Him what to give us, for He can rightly reply that we know not what we ask" (St. Teresa, "Mansions", II, 8).
43-45. Our Lord's word and example encourage in us a genuine spirit of Christian service. Only the Son of God who came down from Heaven and freely submitted to humiliation (at Bethlehem, Nazareth, Calvary, and in the Sacred Host) can ask a person to make himself last, if he wishes to be first.
The Church, right through history, continues Christ's mission of service to mankind: "Experienced in human affairs, the Church, without attempting to interfere in any way in the politics of States, `seeks but a solitary goal: to carry forward the work of Christ Himself under the lead of the befriending Spirit. And Christ entered this world to give witness to the truth, to rescue and not to sit in judgment, to serve and not to be served' (Vatican II, "Gaudium Et Spes", 3). Sharing the noblest aspirations of men and suffering when she sees them not satisfied, she wishes to help them attain their full flowering, and that is why she offers men what she possesses as her characteristic attribute: a global vision of man and of the human race" (Paul VI, "Populorum Progressio", 13).
Our attitude should be that of our Lord: we should seek to serve God and men with a truly supernatural outlook, not expecting any return; we should serve even those who do not appreciate the service we do them. This undoubtedly does not make sense, judged by human standards. However, the Christian identified with Christ takes "pride" precisely in serving others; by so doing he shares in Christ's mission and thereby attains his true dignity: "This dignity is expressed in readiness to serve, in keeping with the example of Christ, who `came not to be served but to serve.' If, in the light of this attitude of Christ's, `being a king' is truly possible only by `being a servant', then `being a servant' also demands so much spiritual maturity that it must really be described as `being a king.' In order to be able to serve others worthily and effectively we must be able to master ourselves, possess the virtues that make this mastery possible" (John Paul II, "Redemptor Hominis", 21). Cf. note on Matthew 20:27-28.
Source: "The Navarre Bible: Text and Commentaries". Biblical text taken from the Revised Standard Version and New Vulgate. Commentaries made by members of the Faculty of Theology of the University of Navarre, Spain. Published by Four Courts Press, Kill Lane, Blackrock, Co. Dublin, Ireland. Reprinted with permission from Four Courts Press and Scepter Publishers, the U.S. publisher.