It seems it's become fashionable these days to believe that happiness is impossible, or even non-existent; that all positive emotions are intrinsically transient. I think this attitude mostly comes from the phenomenon this author describes where you can forget (or just never know) what it's like to be happy. I don't agree with his proposed remedy.

First, I think that very few people have been privileged to enjoy the "simple" lifestyle he wants. Most cultures have either struggled with nature to survive, or avoided that struggle through restless progress. Any culture/organism that was content within it's niche would be outcompeted by fitter cultures/organisms. Ironically, the author is probably one of those best positioned to achieve his ideals; but they don't, because culture has evolved to program them to struggle.

Second, if the bears don't get you, the boredom will. Moderation is key, and it's good to have some mental stimulation too. You don't need to live in nature all the time to be happy. You just need to prioritize spending some time relaxing.