Well, I have to admit I might have been a little extreme in my response. I've heard to many people say only Christians were entitled to it.
I remember this quote in the movie "Shadowlands" where Jack tells the students about longing for something and never getting there. And it describes my experience very well. We will never have completion in this life, never be able to know everything, learn everything, never reach the ultimate point at which we can say "I'm done. This is where I wanted to get, now I can stop trying." Whenever I learn something new, it opens up a whole new word for me and I'm beginning to long for so much more. And that happens with many situations. One thing leads to the next and just when you thought you were close to reaching what you wanted to have, what you'd been longing for, you realize your're far away from it again because something new comes up which you strive for again. And that's life. That's what motivates me to do my very best to make progress in every way I can (and I still fail way too often) and to never stop growing in every way (except maybe for the physical way, that stopped when I was 13 and I don't think I can hope to ever get taller than the 165 cm I've been stuck with for a decade! )
Thus, I also see Joy as sign posts along the way, inspiring me to keep going. I know that at the age of 24 that might sound like I was talking ab out something I still know hardly anything about, but I know someone who is about 20 years older than I and more or less told me the same thing not long ago and she's a very imresssive person.
I just don't think the "unreachable" necessarily needs to be God or Heaven. I have quite a vivid imagination and I'm very certain that there is a lot more out there than we know here on erath... maybe planets with intelligent life which might be much more beautiful, cleaner and a lot more peaceful than earth, dimensions we don't know anything of and maybe even Heaven... the possibilities are endless. The point is that there is something out there which is a lot greater than we will ever be able to imagine and which we will never be able to reach and even though I kn ow that, these moments of Joy keep making me want to try.