Notice how much Peter wanted to be like Jesus. He wanted to do the things that Jesus was doing but Peter was still missing something. His faith was not the same as that of Jesus. Peter did not have the same interior life as Jesus. Peter did not have the same relationship with the Father as Jesus yet he wanted to be the same externally. Maybe we, too, miss the part about going to the mountain to pray as Jesus prayed and so miss out on a deeper relationship with the Father.