“8 Verily I say unto you, ye shall both have according to your desires, for ye both joy in that which ye have desired.”
This is a great principle. God ultimately will give us the desire of our hearts. If we want to serve him, then he will give us the opportunity. John and Peter had different desires. It appears to me that Peter wanted more than anything else an opportunity at redemption. He wanted to be able to show that he was willing to stay with the savior until the end and even unto death. His martyrdom was a fulfillment of a longing that he had. On the other hand, John longed to remain on the earth and to be able to reach the maximum amount of people. He sacrificed a short term dramatic impact for a long term more passive influence. And he sacrificed rest in the presence of God, for perpetual labor. Yet those sacrifices were also according to his desires and brought him great joy.