If you do really want to learn here are some books that I've read that are pretty good. Caveat is that they aren't written by physicians so not all of the information about physiology is 100% correct.
Freediving: the essentials for reaching 65 feet in just two days -Oskar Varg (He has a simpler book too: How to hold your breath for over five minutes with only two days practice)
Manual of Freediving -Umberto Pelizzari
The books are fairly good instruction manuals and coaching tools to help you in breath control and knowing what to expect your body to do while holding your breath.
DANGER: I've got to put a disclaimer that while the chance of dying while holding your breath on land is very small, it isn't nonzero. I would recommend having a practice partner with you or someone nearby who can check on you if they hear a thump, at the very least tell the surgeon to look over the drapes if they don't see you standing there anymore.
Furthermore, your chances of dying go up dramatically if attempting to do breath holds in water...especially by yourself. Shallow water blackout can happen in any depth of water really, so don't practice alone. I've read alot of stories over the years of divers who have gone missing or friends who saw their buddy surface and then watched them slip back under.