Eternity in Heaven - Scary?

[Angrboda]

I came from religions without a concept of heaven. The main problem I have with heaven today is that I can't imagine how it would be capable of existing and still be coherent with human nature. It seems that part of the pleasure of succeeding is knowing that we could have failed. Without that, succeeding at something would seem rather hollow. So heaven would seem to remove the pleasures that come from demonstration of competency and excellence. I suspect that would rob us of a great many positive experiences. So what are we left with once you remove those positives that depend upon the existence of a negative to be meaningful? What do theologians imagine, that it's like one, non-stop crack high? How desirable is that?