This technique does have a cost. Every time you activate your amygdala (which, in turn, activates your sympathetic nervous system, which primes your body for fight or flight mode), it becomes more sensitive both in the moment and the future. You don't want to be in fight or flight mode. It's enormously unhealthy and hard on your body. Moreover, it inhibits your medial prefrontal cortex, which is your "head" in coloquial terms, the region of your brain that houses rational, abstract thought, making it harder to think straight. Fear is the mind killer.