If any of you have played wind instruments you will know what it is like to breathe in and control your breathing out to play the instrument and some of us could hold a note for quite a long time as we control the amount of air exhaled. I used to play a 4 valve Boosey and Hawkes Euphonium for several years in a school band. Also if you sing or hum quietly you can hold a note for a long time. In doing so we are not following the natural cadence of automatic breathing as when we are sleeping. We manage the breathing. Most of the time we do not use the full capacity of our lungs but sometimes you take those deep breaths.
Also if you are not ascending you will not damage yourself by using controlled breathing. Sometimes if I want to get down to a wreck say at 35m - 40m I will go off the boat negative and exhale most of my air from my lungs. I may only take a few sips of air with short breaths to maybe a third of my lung capacity and drift down. Be careful with this, one time my own dive master guide swam down after me as I left no bubble trail and he thought I was an unresponsive diver as I was at such a steep angle speeding down and pulled on my fins.