"You can live forever. It's worth all endeavor." This is more than the lyrics of some lame piece of Kingdumb S***. This is the key attitude of the Watchtower Society, and as long as people believe it, they will bear anything.
It is this attitude that makes people give up so much. You have to throw away your beloved Christmas decorations and crosses when you join the Watchtower Society. You have to break up with a live-in sexual partner or marry them. You have to start wasting your time going door to door. You have to brave hazards from dogs to getting thrown in jail to crocodile infested water. You sweat when it is hot, you freeze when it's cold. You have to drive in the snow and ice, and in other treacherous conditions to get to the meetings and in service. It costs money to drive, to dry clean those suits, and to donate to the organization that makes it all possible.
Now for now, let's assume that you really did have the chance to live forever. Would it actually be worth all endeavor to live forever as a Jehovah's Witness? For one thing, service would vanish as we know it. However, you are still going to have to teach others as fast as they are resurrected. There will be no TV, no Internet, no nothing. Anyone that takes the time out to create value will be destroyed as being unfaithful. Everyone else will find the infrastructure gone. They will find it's not so easy to build those houses without the tools, and it's not possible to build the tools without some of the technology that will be all gone. You will still have the rules to follow, and indeed they could be even stricter than they are now. People might be restricted in traveling to within their own congregation, with the elders being absolute rulers. Or, they could start making new rules (i.e., those new scrolls). Education will be a thing of the past: you learn things according to what the Governing Body of Jehovah's Witnesses wants you to learn. This is exactly what the Catholic church did to start the first Dark Ages. Is it worth all endeavor to live in an endless Second Dark Age?
Besides this, what is the chance that this is actually going to take place? They have blown 1914, 1915, 1918, 1920, 1925, 1941, and 1975 explicitly. They have blown implied predictions for 1984, 1994, and now 2007. At this rate, I feel safe to feel that they are going to blow 2014 and 2034 as handily as they did the others. I don't see peace and security being declared: whenever things are improving in the world, they play that card. But they feel Armageddon is imminent when things are getting worse. What gives?
I, personally, will take my chances and not go back to being one of Jehovah's Witlesses. If I go back and they are right, I live a stagnant life in a new, endless Dark Age. If I go back and they are wrong, I waste my time and that of anyone who listens. If I stay apostate and they are right, I die and miss the new Dark Age altogether. If I stay apostate and they are wrong, I will grow old and die, but I will be able to prevent others from wasting their time in a cult. No matter what, I am better off not returning to the Tower.