I'm looking for a safer way to extend my breath hold time than hyperventilation. One way I find to try to do that is to take in all the breath to fill my lungs up to my throat with my head tilted down just before the dive. Then when the urge to breathe on my chest hits, I try to ignore past it and keep holding my breath past that time. I heard that the urge to breathe on your chest does not mean low oxygen in your body, instead you have high carbon dioxide. In fact, you still have plenty of oxygen in your body when your chest hits the urge to breathe pain while breath holding, contrary to what many people believe about that. So what else could I do? Or is what I'm doing good enough.