I largely agree with those who say heaven and hell are mostly metaphors for how someone approaches living in this world.
On one level, at least, the metaphor seems to be speaking about attachment. If you are emotionally and psychologically attached to things, and can’t step back from your attachments, then it’s going to be hell for you. After all, everything is transitory, and you will suffer — sometimes greatly — when things change.
On the other hand, if you can let go of attachments as spontaneously as a child lets go of someone’s hand, then this world can be something of a heaven for you. It’s transitory nature will often delight you, rather than constantly threaten you. You will be psychologically and emotionally free to enjoy the moment, to take delight in things great and small, even though all things come to an end.
That’s one level of the metaphor. On that level, heaven and hell are about psychological and emotional attachment. The metaphor, like most symbols, might have more than one level, though. For example, it could also symbolize the difference between normal awareness (hell) and mystical awareness (heaven). But even in that case, the metaphor still speaks to us of how we approach this world — rather than speaks to us of some other worlds, some metaphysical realms beyond our ken, some final abodes for our souls.