A friend got me thinking about breathing. She was reading "Breath" by James Nestor, which has been quite popular. I recommended "Conscious Breathing" by Gay Hendricks but I got to thinking about breathing books that have helped me use breathing as a focus of mediation. As I looked over books and mentions of books, I realized that "Breath by Breath" by Prof. Larry Rosenberg was an earlier book in my reading that I really liked. I knew I owned that book in Kindle form and when that is the case, I sometimes make a web page of highlights I have made while reading the book. I searched and yes, I have such a web page here: https://sites.google.com/view/kirbyvariety1/breath-by-breath-notes
These books explain and celebrate the value of using one's breath as a focus of attention while meditating. However, my friend has been suffering shortness of breath, which I think is more of a lung and health problem.
Meditation can be a great assistance with any problem or any success but if I was interested in what I could do about shortness of breath, I would also look elsewhere.