The connection between what the mind perceives and how the body reacts is a curious relationship. Adrenaline flows into our autonomic nervous system when it anticipates that something bad is about to happen—not because something bad is already happening. This hormonal offensive was an essential survival tool for our earliest ancestors that came with our fight-or-flight response, which defends us against immediate threats.

By preparing our bodies to manage danger, these rushes precede both the impending action and our response to it. After all, if we were only filled with jittery energy and super-human strength once that stressor was actually upon us, we’d be sitting in the pit of a saber-toothed tiger’s gut.