John did not live in an ivory tower, but suffered immensely for preaching Jesus as the Lord. As he wrote at the beginning of the Book of Revelation,
“I, John, both your brother and companion in the tribulation and kingdom and patience of Jesus Christ, was on the island that is called Patmos for the word of God and for the testimony of Jesus Christ” (Revelation 1:9).
John was in the tribulation then, he was in the kingdom then, and he was in the patience of Jesus Christ then. These were not simply future realities, something that is still future for us, but the apostle experienced those things during the first century. He experienced tribulation because he had preached the word of God, specifically his testimony of Jesus Christ, and the Roman government banished him to the Isle of Patmos for it.
Follow Jesus, and you shall have tribulation, but you will be in the kingdom, so just be patient as Jesus was.