Jesus is prophesying to Peter about how he would die. Peter was led to the cross by others and was crucified upside down at his request. Peter felt unworthy to be executed in the same method that Jesus was executed. At least eight of the twelve apostles died as martyrs with two, Peter and Andrew, being crucified. There are some leaders that teach that life as a Christian is free of stress and problems. This is not validated by a study of the Scriptures. In fact, just the opposite is taught.
33 I have told you all this so that you may have peace in me. Here on earth you will have many trials and sorrows. But take heart, because I have overcome the world.”–John 16:33 (NLT)
Jesus tells us in this verse that we will have trials and sorrows. Not just the normal troubles of those in the world, but more because we love and obey Him. But He also tells us that we can have total peace in Him. His peace is not a lack of trouble or violence, it is peace that we can access in the midst of all that. Jesus has overcome the world and we are over-comers through Him. We can’t be conquerors and over-comers if there are no problems to overcome or no mountains to conquer.