Breathing. Sounds so simple it's stupid? Not really. Back when I worked as a nurse, I witnessed many patients on ventilators. Not where I want to be, I tell you!
Breathing is so essential, no matter what you're doing. If you're an athlete, an artist, a CEO, whatever. Knowing how to control your breathing is much more than something stupid.
I ran across this book about 18 months ago that I very much recommend, called, BREATHE INTO BEING [see link for details]. In my Transformation Of Self, it has been very helpful.
Do you want to improve your life? Take breathing seriously. Think about it frequently. Everything else will fall into place. It's amazing!