I have thought about death many times and I have to say, it does stir up uncomfortable thoughts. The idea that I will one day have to leave the party, while it goes on without me is not particularly pleasant. Discoveries will occur, technology will advance, culture will progress and evolve, good times will be had, and I won't exist to know of any of it. But another more uncomfortable idea, is that the party will go on forever and I won't be able to leave. I will be forced to stay, consciously aware, forbidden from achieving the peace of mind that death offers.
That is the idea of heaven, and it has never really appealed to me. I don't actually wish for eternal life, as is promised me by Christians. I think of it a rather hideous prospect. I can understand someone who is dying at the age of 40 or 50 to wish for many more years of life, but who in their right mind would actually want to live forever. I mean think about it. To exist consciously forever, as an unembodied spirit, in some sort of fantasy land where detailed descriptions are nil and open to all kinds of conjecture, I think would eventually and inevitably drive one mad.
Even if in heaven you are allowed to indulge in every temptation forbidden to you during your terrestrial life, how long could that entertain you before you inevitably bore of it? If in heaven you become knowledgeable of all the universe's mysteries, so that there are no more to discover, wouldn't an existence without curiosity become one with no purpose? What would you do in this situation after, say, a thousand years of existence? What about ten thousand, or a hundred thousand, or a million? Even after all of this time, there is still eternity to look forward to. What could possibly keep your consciousness occupied for eternity?
The only thing unavailable to you in heaven is death. Death is the one thing you could never and can never have. You cannot die, you cannot cease to exist consciously. God wouldn't allow it. He has determined that the consciousness of every conceived human being exist eternally as a "reward". Since we all want what we can't have, you would eventually become obsessed with death, but it will always be out of reach. You will be able to have every possible experience except death, but you must exist eternally, that's the whole plan.
Intellectually, I have never heard a Christian plausibly explain these problems to me. I for one am looking forward to not existing consciously. Sometimes it is my conscious itself that drives me crazy. I think too much about too many things and I wish I could turn my mind off sometimes. I actually do hope that death is eternal non-existence. I don't want to be aware of my surroundings forever, and the very idea of it make me depressed. So when theists think they are making the offer no one can refuse, (that of eternal life) I can say to them that the very idea seems like hell to me. It is a good thing that we have no serious evidence that consciousness exists beyond the death of our brains. I certainly sure hope it doesn't.