3.5 Second Box Breath This is a slightly faster version of the standard 4-second version of box breathing. The Rhythm: Inhale: 3.5 Seconds Hold: 3.5 Seconds Exhale: 3.5 Seconds Hold: 3.5 Seconds You take 4.3 breaths per minute when doing this exercise. Breathing in a slow, steady rhythm helps signal safety to your nervous system. It activates the parasympathetic "rest and digest" response. Your muscles relax and your heart rate may go down. You may even notice your mind getting quieter. With reg