Praanaayaama is often explained as "breath control" and many yoga teachers teach it this way, using breath ratios and counting. That school of praanaayaama uses the will to hold the breath. The word "control" has unfortunate connotations and is out of synch with the TNB viewpoint of praanaayaama. The word "control" implies a controller who is using what they think they need, on the breath.
"Breath Channeler" is a better phrase, that is more inline with This Next Breath viewpoint and practice. You guide the breath left ... and you guide the breath right. That's all. Most of all "Let it flow. Let it go. Surrender into the Praana. Practice happy. Practice a massive amount of time each day." That is the most successful approach, from a biological standpoint.
Based in the teachings of Swami Kripalu, the TNB approach emphasizes listening, curiosity, spontaneity, love, devotion and joy.
There is nothing more miserable than breath holdings, breath ratios and forcing the breath in a box it doesn't want to go into. The messed up mind doesn't really know what's its doing anyway with inflicting ratios. It is more fun, easier and much more delightful to bow down to the Breath (Praana.) Let the Praana decide.
I like the metaphor of a train track engineer who switches track. Here comes the train of the breath, just switch the track and that is your only job. It is so simple. There really is very little involvement of the personality and its neuroses. You listen. You respond sensitively to what the Breath/Spirit is communicating right now. Change tracks. And the most amazing things start to happen.