Because when you're in a fight or flight scenario, it's the adrenaline rush (or endomorphins, depends if you're predator or prey in your mind), it makes everything spin faster Whatever you do, don't stop breathing, breath as normally as possible, remain relaxed, no apnea, don't close your eyes, ever, unless it's absolutely necessary because gas for instance. Being out of breath is the last thing you need, and apnea even for a couple of seconds 4 or 5 seconds is the express way to get there in a fight, and once you're 'out of gas' you're toast essentially, you end up barely able to throw an attack or raise a defense There's no time to think in a fight, the thinking has to be done before or after the fight, not during, it gets in the way