To manage anxiety while speaking, adopt the 'One Idea, One Breath' model. The key is to make your out-breath significantly longer than your in-breath while delivering a single idea. This extended exhalation activates your parasympathetic nervous system, lowering your heart rate.

Functions we consider involuntary, like heart rate, immune response, and body temperature, can be consciously influenced. By controlling the breath, we can directly tap into the autonomic nervous system, enabling us to shift between a 'fight or flight' state and a 'rest and digest' state to manage stress and improve health.

A double inhale followed by a long exhale, the 'physiological sigh,' is the fastest way to calm down. This built-in reflex, controlled by a dedicated brain circuit, maximally inflates the lungs to offload CO2 and immediately slows the heart rate via the vagus nerve.

Deep belly breathing, with a focus on a long exhalation, slows the autonomic nervous system and calms physical symptoms of anxiety like a shaky voice. It's a physiological hack to manage the fight-or-flight response.

The counterintuitive advice 'if in doubt, breathe out' is powerful. Focusing on a full, elongated exhalation not only activates your calming nervous system but also ensures a natural, reflexive inhale will follow. You don't need to consciously gasp for air; your body will handle the in-breath automatically.

To manage public speaking anxiety, communication expert Matt Abrahams advises focusing on deep belly breathing where your exhale is twice as long as your inhale. Just two or three of these breaths can slow your nervous system, lower your heart rate, and normalize your voice, providing an immediate calming effect.

The parasympathetic nervous system (the "parachute" or calming response) activates faster than the sympathetic (fight-or-flight) system. You can begin to trigger this calming, vagal nerve response almost instantaneously, within a single controlled breath.

Shallow chest breathing during stressful situations creates a vicious cycle of anxiety. In contrast, deep belly (diaphragmatic) breathing is a direct physiological intervention that lowers your heart rate and calms your nervous system, giving you more control and presence.

The fastest way to reduce stress is a long, deliberate exhale. This action activates a specific vagal nerve pathway that communicates with the heart's sinoatrial node, directly slowing your heart rate and shifting you toward a parasympathetic (calm) state.