Completely anecdotal experience: a year ago, after getting started with meditating regularly, I realized breathing "deeply" (through the nose and "with the bell

Completely anecdotal experience: a year ago, after getting started with meditating regularly, I realized breathing "deeply" (through the nose and "with the belly") for more than 5 minutes straight, had a big impact on my energy levels and focus for a few hours. So I decided to do it the whole day for a full week. It was incredible, my mind was completely clear all the time, I felt great, and my wife noticed that I even stopped snoring. Since then I've done it again a few times, but can never sustain it for more than a few days. It's super simple, but building the habit is very hard.