People often enjoy talk about other persons. The disciples, too, gladly tell what other people think of Jesus. Only Peter is bold enough to position himself: "You are not merely some special man, but the Messiah, the Son of God." With this profession he makes a great advance in his life of faith and his relationship to Jesus.
Jesus demands a decision. He who decides for Jesus is unable to continue living simply as he was before, as he would without Jesus. He is taken into the life of Jesus, which entails more suffering as well as more joy.
Jesus tells the Apostles, without pulling any punches, the suffering that he will endure, and they as well. Peter, perhaps thinking that Jesus has gone off the far end, reproaches him. Yet Peter has seminally what he needs to accept this part of Jesus's message: his profession of faith in Jesus, which can lead him to understand the meaning of the suffering that Jesus takes on, and that Peter himself will have to endure.
Jesus is the suffering servant, his suffering and death a sacrifice to redeem his people. It is not, however, his suffering and death per se, as a material price, that redeems, but his love, a love that does not reject suffering, when it is necessary.
We frequently need such love in our lives, too. In many situations a way out is possible only at the price of a sacrifice: crises in a relationship, enduring conflicts, fidelity in difficult situations; often it is only love that is ready for sacrifice that can help. To take just one example, to resolve a conflict and realize healing in a wounded relationship, we must often be ready to give up on coming out as the "winner", or even be willing to have just a little bit the feeling of "losing". Genuine reconciliation doesn't have a loser, since both sides are the better for it, but sometimes we still have the feeling of giving something up and in this sense of losing.
How do we stand on the issue of making sacrifices for Jesus, of entering not only into his joy, but his suffering as well? Do we think that as believers, life will be easier and we will have fewer problems, because God solves them for us or doesn't let them arise in the first place? It can happen, particularly at the beginning of the way in faith, that God makes the way attractive, to encourage us, as one may reward a child with sweets. But at some point we must cease to be dependent on these sweets, whether that is interior consolation or providential avoidance of exterior difficulties. The deepest joy in faith isn't found in God's preserving us from all evils and difficulties, but in being united with HIM, even then, indeed especially then, when loves calls for a sacrifice.
As gratitude gives our joys a deeper meaning, as a gift from one who loves us, so readiness to sacrifice gives our sufferings a deeper meaning, as being an instrument of salvation in Christ.
In the measure that we make these two fundamental attitudes, gratitude and making sacrifice, "offering them up" for and with Jesus, we will experience the fulfillment of Christ's promise, "seek first the kingdom of God and his righteousness, and everything else will be given to you as well." We won't always have everything that we might immediately wish to have, but in what we do have and in what we don't have (or what we suffer), we will find ourselves to be rich in him.