I, John, your brother who share with you in Jesus the persecution and the kingdom and the patient endurance, was on the island called Patmos because of the word of God and the testimony of Jesus. (NRSV 1:9)
I John, who also am your brother, and companion in tribulation, and in the kingdom and patience of Jesus Christ, was in the isle that is called Patmos, for the word of God, and for the testimony of Jesus Christ. (KJV 1:9)
Right away, John is letting the reader know that he feels their pain.
Do not fear what you are about to suffer. Beware, the devil is about to throw some of you into prison so that you may be tested, and for ten days you will have affliction. Be faithful until death, and I will give you the crown of life. (NRSV 2:10)
Fear none of those things which thou shalt suffer: behold, the devil shall cast some of you into prison, that ye may be tried; and ye shall have tribulation ten days: be thou faithful unto death, and I will give thee a crown of life. (KJV 2:10)
This is part of one of the letters to the individual churches. Jesus wants them to know that trials are coming, but to stay strong. He's also very serious about the "faithful until death" part. No chickening out is allowed.
A great portent appeared in heaven: a woman clothed with the sun, with the moon under her feet, and on her head a crown of twelve stars. She was pregnant and was crying out in birthpangs, in the agony of giving birth. (NRSV 12:1-2)
And there appeared a great wonder in heaven; a woman clothed with the sun, and the moon under her feet, and upon her head a crown of twelve stars: And she being with child cried, travailing in birth, and pained to be delivered. (KJV 12:1-2)
If the Woman is the Church, this image of her is a pretty great call to endurance. She's in a huge amount of pain, but she keeps going because she knows she's going to bring something beautiful and new and precious into the world.
They have conquered him by the blood of the Lamb and by the word of their testimony, for they did not cling to life even in the face of death. (NRSV 12:11)
And they overcame him by the blood of the Lamb, and by the word of their testimony; and they loved not their lives unto the death. (KJV 12:11)
Again with the dying. The faithful are clearly supposed to follow the example of Jesus—believe in God, no matter what the cost.
Here is a call for the endurance of the saints, those who keep the commandments of God and hold fast to the faith of Jesus. (NRSV 14:12)
Here is the patience of the saints: here are they that keep the commandments of God, and the faith of Jesus. (KJV 14:12)
The whole book is actually a call for endurance, but the occasional reminder is nice, too.
I heard a voice from heaven saying, "Write this: Blessed are the dead who from now on die in the Lord." "Yes," says the Spirit, "they will rest from their labors, for their deeds follow them." (NRSV 14:13)
And I heard a voice from heaven saying unto me, Write, Blessed are the dead which die in the Lord from henceforth: Yea, saith the Spirit, that they may rest from their labours; and their works do follow them. (KJV 14:13)
Another reward for the martyrs. First crowns, now a rest from their labors. This is also a promise that God has seen and knows what they've done for him. And God doesn't forget when people go to bat for him.
I also saw the souls of those who had been beheaded for their testimony to Jesus and for the word of God. They had not worshiped the beast or its image and had not received its mark on their foreheads or their hands. They came to life and reigned with Christ a thousand years[…] Blessed and holy are those who share in the first resurrection. Over these the second death has no power, but they will be priests of God and of Christ, and they will reign with him a thousand years. (NRSV 20:4, 6)
And I saw thrones, and they sat upon them, and judgment was given unto them: and I saw the souls of them that were beheaded for the witness of Jesus, and for the word of God, and which had not worshipped the beast, neither his image, neither had received his mark upon their foreheads, or in their hands; and they lived and reigned with Christ a thousand years[…] Blessed and holy is he that hath part in the first resurrection: on such the second death hath no power, but they shall be priests of God and of Christ, and shall reign with him a thousand years. (KJV 20:4, 6)
Perhaps the nicest gift of all, according to Revelation—the martyrs reign with Christ in Heaven. That's how highly regarded these guys were in the early church.
I heard a loud voice from the throne saying, "See, the home of God is among mortals. He will dwell with them as their God; they will be his peoples, and God himself will be with them; he will wipe every tear from their eyes. Death will be no more; mourning and crying and pain will be no more, for the first things have passed away." (NRSV 21:3-4)
And I heard a great voice out of heaven saying, Behold, the tabernacle of God is with men, and he will dwell with them, and they shall be his people, and God himself shall be with them, and be their God. And God shall wipe away all tears from their eyes; and there shall be no more death, neither sorrow, nor crying, neither shall there be any more pain: for the former things are passed away. (KJV 21:3-4)
Again, if you stick it through to the end, God promises the pain will end. Must have sounded very nice to these people who were going through quite a lot.
Those who conquer will inherit these things, and I will be their God and they will be my children. (NRSV 21:7)
He that overcometh shall inherit all things; and I will be his God, and he shall be my son. (KJV 21:7)
Believers are often referred to as conquering, probably because by staying faithful to God they've managed to defeat the pressure to conform to the Roman way of life.