[photochemsyn]

The article briefly mentions "diaphragmatic breathing" without going into it, but it's one of the best ways to do breathing exercises in a slow, controlled and relaxing manner while sitting upright at a desk. It's also a part of the training for vocalists, and that a good source on how-to guides, e.g.

https://www.singwise.com/articles/correct-breathing-and-supp...

> "It is also important to note that, in voice pedagogy, 'breathing from the diaphragm' and 'breathing from the belly' are not viewed as being synonymous. The breath support technique that is widely referred to as 'diaphragmatic breathing', (when correctly executed), should not be confused with 'belly breathing'. Unlike 'belly breathing', 'breathing from the diaphragm' involves no pushing or forceful expulsion of air, and is the natural, correct, safe, gentle, internationally accepted method of supporting the singing tone. In diaphragmatic breathing, the tone rides on a minimal and steady stream of air, which brings stability and consistency to the tone."