Splash Your Face with Cold Water

Humans have what's called the mammalian diving response: a reflex that "flicks on" when we're submerged in cold water or even do something as simple as splash our faces with water. When this happens, our heart rates automatically slow down and we breathe more deeply. This helps us to calm down. It's similar to the goal of things like deep breathing, but taking advantage of the diving response by splashing your face with water can kick-start and speed up the process.