My own experimentation really came from yoga breathing. On my uphill cycles I started, almost without thinking, to breathe through the nose and expanding my diaphragm. I also tried it when I was out of breath -intead of just shallow panting- and just during any walk. Other than for trying to get more air deeper into my lungs, for me it was also about the feeling of expanding my ribcage to reduce the feeling of tightness. A little bit like what happens when you arrive somewhere in nature and it's a glorious day and you almost instictively take a couple of deep breaths to take it all in and to let go of the stress and worries. About taking larger breaths, one things that I would say is that some people might feel that their nasal cavities are too narrow and they really have to work to get the air in, which in turn prevents them from breathing slowly. It shouldn't be too long beforethey realise that focusing on the nostrils will give them a sense that you can use the muscles around the nose to open up your nostrils and get more air down to the lower lungs. You can practice that any time of day, and once you get it breathing will definitely improve.
