Like most openminded atheists I don't argue that God can not possibly exist. The possibility that Jehovah and his heaven and his hell do exist is not the point, as far as I'm concerned. They might well exist for all I know. In the absence of evidence, who can say? I just can not force myself to believe in them any more than faithful Jews, Christians, and Muslims can force themselves to believe in Thor, Asgard, the gods of Olympus, Visnu, and Shiva. Disbelief is not limited to us atheists. In fact, I disbelieve in only one more god than Pat Robertson disbelieves in (assuming Pat is sincere in his belief in a god).
I used to be one of those people who build their present lives on settled though unprovable concepts of an afterlife. Overall, the experience was not a positive one, and it took me years to get past the bad juju of force-feeding myself on the unfounded guilt, fear, and hope that came with such a belief system. I will admit that in my believing years I experienced a clearer sense of belonging than I do presently. Of course, back then I had youth going for me, as well as a simple faith that a blood sacrifice 2000 years ago was, despite contradictory evidence, making everything copacetic today. But the price of belonging was self-denial, unarguably a touchstone of the Christian faith, and self-humiliation (or humility, if you prefer). My acceptance at the churches I belonged to required acquiescence to the prejudices, politics, and even decorating tastes of my fellow church members, so I, the actual "I," never belonged even when I thought I did.
So how do I feel about not going to heaven? Not much, apparently. The few times over the past thirty years when I have felt close to death, the idea of my eternal destination did not occur to me even once. The only thought in my head, in the two experiences that I can clearly remember, was "Okay. This could be it." Nothing deeper, more profound, more poetic, philosophical, or life-changing than that. I was thinking "Okay I might be dying" on the same level as I think, once or twice a day, "I might be hungry." I figure that most atheists' responses to death must be deeper, more dynamic than mine, but this "meh" response to everlasting annihilation is all I got. I've had one night stands that have had more impact on my life than this.
The idea that the ME that I have come to love over the years will probably not live to see 2040 has no more effect on me than that this ME missed out on the golden age of Hollywood in the 1930s. Of course, I would prefer not to miss the next Jessica Lange performance and I may never see Paris, but on the whole I am pleased with my life as it has been so far. (I'm told I was a self-satisfied baby too, never crying or throwing temper tantrums, so I was probably born with this sort of equanimity ... and, perhaps, lack of gumption.) I have more fear of outliving my usefulness to others or outliving significant others than fear of my cessation of being. Further, I am particularly pleased with my post-faith years, during which I have learned more about love, friendship, generosity, magnanimity, peace of heart, wisdom, and kindness than I ever learned as a fundamentalist Christian, when those words or ones like them were part of the requisite vocabulary, often repeated hourly with phony high spirits like the laugh tracks on 1960s sitcoms.
Do I want to die right now? No. Definitely no. But if it happens, it happens, and I have enough leftover blind faith in providence (but WHOSE providence?) that I figure death will come at the right time, whatever "right time" means. I call this "blind faith" because everyone I know who has died has not died at any time I would call "right." Statistically, then, my death will likewise be poorly timed, inconvenient, and, in the larger scheme of things, insignificant. But why worry about that? Worry is the unpleasant side effect of hope and fear. And who has time for that?