I prefer to keep my mouth closed and use my nose for breathing.
To each his own. Of course if this is how you prefer to breathe, you realize that are sending out the same unfiltered germs and viruses you take in.
It is possible that I am a bit jealous, so don't take what I posted to heart. I have asthma and a deviated septum. Even remembering to breath in through my nose unless I really concentrate on it makes me feel like I am not getting enough oxygen. When I was young, swimming was my sport. You can't imagine how challenging that was. It did teach me rhythmic breathing. I've never been good at holding my breathe.