Happy to offer a free virtual session for founders if there is interest here, as our work is always gifted.
If you want to take a low-woo course on it, here's one: https://www.nsmastery.com/ (I know Jonny, but I'm not affiliated and I haven't taken his course.)
As an aside, and in all seriousness, how well would this works for a self-medicated functional alcoholic who thinks breathing exercises involve rolling a cigarette first? Does one have to be one of the self-congratulatory "healthy" and swear off vices to benefit from this, or is it something you can do before you head off to the bar?
This is... well it's much more of a direct physical response so no you don't need to have any particular uh mental states or be self-convinced of some woo.
Have you ever hyperventilated until you felt lightheadded? You can do this on purpose right now with no training or conditioning your thoughts or anything and there you go, you've got neurological effects from breathing.
This technique is just advanced "hyperventilating until you feel lightheaded".
If you've got a medical condition you might want to reconsider or be very careful about getting the right information before you try.