There are a lot of peculiarities to this text for April 25. First is the fact that chapter 21 comes after John has seemingly already ended the book at chapter 20, v 31.
The 2nd is that, like in Luke, there's this thing about fish and the resurrected Jesus. I know we splace the word ichthos around, and understand the disciples as fisher's of humanity, but why is it that in actual church practice fish plays such a small role, whereas the other foods of Jesus have found a central place in the liturgy? Clearly, the Lord's meal is a meal in anticipation of his death, therefore, "As often as we eat this bread and drink this cup, we proclaim the Lord's death until he comes." But why not also, at some place in the churches life, "As often as we eat this bread and roast this fish, we proclaim the Lord's resurrection until he comes." There is even a direct instruction from Jesus, "Come and have breakfast" (v. 12).
Then there's the whole thing with Peter's clothes. He puts on clothes before jumping in the water, because he was naked in the boat. This is one of the finest descriptive scenes in all of John's gospel, Peter stumbling and splashing out of the boat while pulling his clothes on rather than taking them off in order to swim. Certainly this is instructive for our understanding of the Petrine office. :)
Later, Jesus' words, "when you were younger, you used to fasten your own belt and to go wherever you wished. But when you grow old, you will stretch out your hands, and someone else will fasten a belt around you and take you where you do not wish to go."
I believe this word of Christ is related to the child/adult distinction already found in the text. Jesus calls the disciples his children. But by the time Peter is crucified, he is no longer child, but adult. And adult in a way much different from what we normally imagine, adult as free and in command. No, adult means going the way of Christ, growing up in the faith.
I've been reading Robert Bly's The Sibling Society of late, one of the most prophetic, earnest, and winsome texts I've ever read, and I commend it to anyone trying to figure out this relationship between Peter and Jesus, among other things- especially how it might be preached today. Jesus takes Peter through a profound process, the trifold questions making him into a shepherd, the description of Peter "dressing" Peter up into something different altogether. Shepherd and slave simultaneous. Both of these simultaneities united in the simple instruction, "Follow me."