Mark 8: the Messiah and the cross

Jesus had power and will to restore people. No wonder the crowd was following him for three consecutive days and hungry. Jesus wanted to feed them because he was afraid they would faint along the way. He multiplied the bread to feed the crowd by the second time. How can the Messiah with such power headed to the cross?
We read:

29 He then asked, “And you—what are you saying about me? Who am I?”
Peter gave the answer: “You are the Christ, the Messiah.”

It is easy to understand that the one who restored people, feed them, preached to them, loved them was the Messiah, but we read:

30-32 Jesus warned them to keep it quiet, not to breathe a word of it to anyone. He then began explaining things to them: “It is necessary that the Son of Man proceed to an ordeal of suffering, be tried and found guilty by the elders, high priests, and religion scholars, be killed, and after three days rise up alive.” He said this simply and clearly so they couldn’t miss it.

Jesus said that he would be killed. Peter couldn't believe on it! Would the powerful and merciful Messiah be killed? Peter seemed not to believe that would rise up after three days.
Jesus told his disciples:

34 And He summoned the crowd together with His disciples, and said to them, “If anyone wants to come after Me, he must deny himself, take up his cross, and follow Me. 35 For whoever wants to save his life will lose it, but whoever loses his life for My sake and the gospel’s will save it. 36 For what does it benefit a person to gain the whole world, and forfeit his soul? 37 For what could a person give in exchange for his soul?

I, as a Christian, am aware that I must deny myself take up my cross and follow Jesus. I am not important, Jesus is important. If he that is the son of God, didn't run away from the cross should I?