The excitement of the crowds, coupled with the unpredictability of Jesus' itinerary, led the disciples to accept a day-by-day lifestyle. They did not seem to have a long term perspective, except perhaps in their imagination that Jesus would become king, enhancing their supporting roles in His team. So Matthew records three reality checks, in which Jesus plainly tells them that He would die at the hands of violent men (Matthew 16:21; 17:22-23; 20:17-19).
 
The first was after Peter's declaration that Jesus was the Christ (Messiah), when the disciple rebuked Jesus for even thinking He might be killed: Jesus said strongly, "Get behind me Satan …". The reality check in today's verse came after the transfiguration. The third came just before the mother of James and John asked for her sons to have very important jobs in the government when Jesus became king of Israel. Jesus would not allow fantasy, wishful-thinking and proud ambitions to stand in the way of the truth of His salvation plan.
 
Even though Jesus promised resurrection, the disciples could not understand, and reacted as though they had not heard. They only understood death, and resisted that idea because it would be the end of their dreams. What they needed to grasp was that Christ's resurrection would become the foundation of their hopes. That would become the gospel which they would take to the world, and upon which the church (including us) would be built.
 
God does not bring grief to the believer except to discipline and strengthen us. Hebrews 12:5-6 says, "My son, do not make light of the Lord's discipline, and do not lose heart when he rebukes you, because the Lord disciplines the one he loves, and he chastens everyone he accepts as his son." Lamentations 3:31-33 says, "For no one is cast off by the Lord for ever. Though he brings grief, he will show compassion, so great is his unfailing love. For he does not willingly bring affliction or grief to anyone." God's reality checks are not to take away hope but to establish hope on the right basis. So do not be discouraged but allow reality to displace fantasy so that you may be confident in God's love in salvation and His provision for your future.