Heaven and Hell are a state of minds.
you can call those states of mind those words, or you can eschew religious lingo altogether and call them something else. i don't find this assertion any more useful than saying "god is love" or "god is everywhere" in an attempt to redefine and even recycle religious lingo. it's not necessary, it confuses some folks and it's not even especially original. a tree is a tree and a bad situation is a bad situation. they don't have to be god and hell. those words already have meanings.
Yes, we can put ourselves through heaven or hell in our minds, but there are also forms of heaven or hell that are humanly constructed, and yet others are pure nature. So, there are at least 3 types of heaven/hell that I can imagine, none of them supernatural.
Hell, as I understand it, is more of a state where one is being tortured in various ways, in which life becomes unlivable or nearly so. That sounds like a lot of lives currently being led by many many people. Heaven, presumably, would be the opposite of that. Also presumably, that only applies to the rich and powerful.
ORIGINS OF HEAVEN AND HELL - A SIMPLE EXPLANATION
I think the origins of heaven and hell are in the stories told by traveling story tellers. It was an attractive profession when being able to have a full meal, clothing and shelter were thought to be a good life. Story tellers were highly sought by the nobles, royalties and rich families as much they were by the middle and lower classes.
These story tellers told of the places that had pleasures, peace, luxury and peace people could dream of. People listened with a shock and awe. They were told if they worked hard and perform good deeds, their luck would take them there in next life. But the message was the good, model people lived in happy places with no sorrow. Most places in Europe were though to be better civilized societies.
Story tellers also told of barbaric places of injustice, risk, cannibals and violence. Most of these places were thought to be in Latin America and Africa. This was hell.
After this, the local medicine men took over and put their own spin on the stories and began telling people how things must be, how the medicine men and elders must be followed and what punishment they would get from fate if they didn't. The savvy people in tribes so this as an excellent opportunity to grab power. Nothing else got their attention as much as the lure of something very good and a punishment for disobedience with the fear of an invisible power. So, the mumbo jumbo grew and grew and grew ridiculously into faith, religion and Gods.
Just look at the similarities among stories of Odysseys and Lord Ram, Moses and Lord Krishna, 8 virgin mothers across epics in various cultures. These similarities came from story tellers recycling stories from one land to another.