Peter acts as we expect - he operates in the Kingdom of the world, in fear, self-protecting and reacting. Jesus operates as we wouldn't expect; he is in a different reality, the Kingdom of Heaven. He is abiding in the perfect love of the Father, and it drives out all fear. Thus, he can give his life away. He can lay it down. Because of Jesus, we too can live this reality, this existence, rooted in the Kingdom of Heaven, and we too can give our lives away.