Reddit mentions of Prana And Pranayama

Many aspects of Hatha yoga can help with this. Pranyama is especially helpful which you can learn some about in the book Prana and Pranyama but it is something to start slowly with and it is best to have a teacher. Having a dedicated Asana practice for a while (like a year) beforehand I think is also prudent. Asana practice will also help balance the hormones and neurotransmitters (it is claimed and subjectively it seems effective).

(Edit although one simple pranayama that is immensely helpful and not dangerous is long slow breathing with the breath expanding into the belly. Being mindful during the day to breath deep into the belly (diaphragm expanding to fill the lower lung lobes) is very helpful it activates the parasympathetic nervous system. Especially focusing on long and deep exhales. Just spending some time every night in "constructive rest" breathing deeply and slowly into the lower lung lobes has helped me immensely during depression episodes. Most people hold onto lots of tension in their diaphragm. )

What does a master of breathing do? How does a master of breathing breathe differently than a baby?

I would love for you to answer these questions, as I'm intrigued.

But what I can say now is that if you want to delve into breathing exercises, the yogic system of Pranayama is where it's at. The Wim Hof breathing you have tried out is a form of Pranayama.

It's best to start with live instruction, so if I were you I'd find a course in your area. But one book I have read on the subject is this:
https://www.amazon.com/Prana-Pranayama-Swami-Niranjanananda-Saraswati/dp/8186336796
It's quite a comprehensive manual on the art of breath control.

I can highly recommend the book prana and pranayama from Swami Niranjanananda Saraswati

https://www.amazon.com/Prana-Pranayama-Swami-Niranjanananda-Saraswati/dp/8186336796