Thinking of all the people whose only breath-holding experience is to do the single Wim Hof exercise. This is what you’ve missed: -hyperventilation is a physiological trick that artificially delays the urge to breathe. Systematically doing that has prevented you from developing the ability to regulate your mind and nervous system while under pressure; the moment the effect of the trick wanes, you crumble. -holding your breath after an exhale means low intrapulmonary pressure during the hold. This has prevented you from developing tolerance to high intrapulmonary pressure, as well as from increasing lung elasticity and acquiring greater vital capacity. Vital capacity is an essential health and longevity marker. -CO2 tolerance: whereas it’s not the only reason that triggers to breathe, purging a lot of CO2 out of your body before holding your breath to delay the urge to breathe and holding your breath for much shorter durations than if you had taken a large inhale before each holds has obviously prevented you from dealing with substantial CO2 blood levels. So it’s prevented you from developing real CO2 tolerance. As for exhale holds stimulating the vagus nerve and triggering a calming effect by shifting the nervous system into the parasympathetic mode more than after an inhale: it’s a myth. There’s no scientific evidence that holding the breath after an exhale calms the nervous system more than after an inhale. If you want way more benefits from breath-holding practice, do them on FULL lungs. And if you want even more beneficial outcomes, learn the specific meditation techniques that quiet the mind and to intentionally relax the nervous system, but not through a hyperventilating trick that can be “taught” by a 6 years old kid.