I honestly have no worthwhile answers for this. Outside of the development of some sci-fi level neural implant that allows us complete control over our felt experience, I don't believe it's possible to achieve the sort of state you describe to the extent it no longer causes any discomfort or conflict with human physiology. Drugs, perhaps of the psychedelic variety, are a very imperfect alternative to the above, but that at least carry with them the potential of transforming oneself into something more bearable than what can otherwise be achieved sober. Of course, this is hardly much of a solution and is also predicated on the assumption that they don't create more harm than they might alleviate. Not to mention that once one is no longer high, the same old problems tend to come roaring on back.
I'll make a quick mention of one other thing though. It has to do with NDEs (near death experiences). Specifically the NDE of someone called U.G. Krishnamurti, and the aftermath he experienced afterwards which he referred to as the "calamity". In his case, he sought spiritual awakening/full control over himself for decades, but it wasn't until his near death experience that he finally achieved a true form of egoic transformation that lead to much of his biological instincts being more or less either permanently disabled, or completely under his own control. As opposed to being some inert vegetable, he was actually still quite jovial and rowdy. By all accounts, including his own, he had achieved a state of complete emancipation from feelings which otherwise compose the darkest and most bothersome parts of the human psyche. However, he was often quite clear that there was absolutely nothing other people could do to achieve the same thing. Even having a NDE was no guarantee. According to him, it either happens to you or it doesn't. Anyone who said otherwise, like other gurus offering pathways to a similar kind of enlightenment, were, as he put it; "lying, swindling, god damned bastards". UG was a very refreshingly honest guy in this regard and, as far as I'm concerned, one of the few people EVER to tell others straight up that we're basically enslaved to our ego and personal biology, save for some extreme outcome of chance of the kind he experienced and which was essentially impossible to replicate. No amount of mucking around with various doctrines, philosophies, or spiritual teachings, will ever change that. It's a switch that either gets flipped inside you, or it doesn't. There's nothing that most of us can do to force it, outside of perhaps suffering a near death experience like U.G. did.
There's a great chapter in Thomas Ligotti's TCATHR that focuses on this exact sort of thing. Ligotti comes to a similar conclusion that essentially the only people who have ever achieved true freedom from the human condition, are those who have had very close brushes with death, precisely in the form of a NDE, and he cites a few examples, including U.G., to show that this is the case.
In my case, I take the Cioran approach for lack of any better option. That is to say that, like him, I endure myself. That's basically it.
And below is a good example of U.G.'s overall bluntness when it comes to this sort of thing, for what it's worth.
This second video is probably a better place to start and does a good job of illustrating his combined detachment and retained joviality.
