I agree that it's all very interlinked, but that doesn't mean there's no distinction. Changing your way of thinking is purely psychological, whereas changing what you eat is both.

> id add that this is why “mastering your emotions” using the control sense of mastering, doesn’t make sense.

I'm not sure I understand what you mean here, it seems to contradict what you said in the earlier sentence? For example, if you have migraines due to stress, and you learn to control your emotions, you could reduce migraines. Breathing slowly is one way to do so, but there's also a lot of more or less purely psychological ways of doing it (e.g. CBT).