You are so right. I discovered the power of deep and long breath only some years ago, and since then trying to use it to calm myself in difficult periods, and very recently trying to have a small breathing session at least 3/4 days a week (started doing daily after I woke up, but being consistent ia ao fucking hard, having to go to work doesn't help 😅).
The results are not always the same, and sometimes you can feel it works much better than others, but I always feel a sense a relief after, it helps to channel better internal energy, and to let it flow when I feeling it stuck..
Once, one of the first time I did it, was able to have an unbelievable experience of transcending my body and consciously flying over the sea and reaching a specific place, it was all so vivid.. never reached that level of 'concentration' again, unfortunately.. 😅🥲