20,000 Breaths
What's actually happening every time you inhale
You’ll take around 20,000 breaths today. How many will you actually notice?
For most people, the answer is close to zero… because that’s how breathing works.
Breathing doesn’t need your attention. It just happens, whether you’re in a meeting, asleep, mid-sentence, or completely somewhere else. Your lungs have been running without supervision since the moment you entered the world, wailing at everyone in earshot.
Here’s what makes breathing unlike anything else your body does, though. It’s the only automatic function you can quickly and easily take over whenever you want. Your heartbeat doesn’t work that way. Digestion doesn’t work that way. You can’t lower your blood pressure just by thinking it.
But you can consciously control the breath – slow it down, deepen it, adjust the rhythm entirely – and something measurable shifts almost immediately.
That’s worth looking at once. Here’s what’s actually happening.
What Happens When You Inhale
Your diaphragm is a dome-shaped muscle sitting just below your lungs. When you inhale, contracts and flattens downward. This creates a drop in pressure inside your chest cavity, and air rushes in to equalize it. You’re not really pulling air into your lungs; you’re creating the conditions for it to arrive.
That air travels through your trachea (windpipe), branches into the bronchi, then narrows into bronchioles (smaller branches) until it reaches your 480 million alveoli. The alveoli are tiny air sacs but you’ve got so many, they take up a surface area of around 750 square feet! Within the alveoli, oxygen passes from the air into your bloodstream and carbon dioxide moves out.
The whole exchange takes less than a second.
Meanwhile, your heart does something most people never notice: it speeds up slightly on every inhale. Only a beat or two, but it happens consistently, reliably, every single time. This is called respiratory sinus arrhythmia, which sounds terrifying but is actually a sign of a healthy, responsive nervous system. A heart that adjusts freely with your breathing is a heart in good communication with your brain.
What Happens When You Exhale
When you exhale, your diaphragm releases and rises back to its resting position. The air, now carrying carbon dioxide collected from your cells, moves out the same way it came in.
And your heart slows back down. Again, subtly, but measurably, on every single exhale. (You’ve been doing this 20,000 times a day, your whole life, without knowing it!) If you lengthen the out-breath, that helps to stimulate your vagus nerve. In turn, this activates your parasympathetic nervous system – the part associated with rest, recovery, and calm.
Don’t forget the pause. Most people think they breathe in a continuous loop with the inhale immediately flowing into the exhale, leading right into the next inhale, again and again with no real gap. But there’s a natural resting point at the end of each, a moment of stillness before the breath completes (after the inhale) or begins again (after the exhale).
Most of us move through it without stopping. But that pause is worth noticing. It’s a moment of quiet that’s always available to you (and only you!).
Try It Once
You don’t need a technique for this. You’ve done it thousands of times today already.
Just take one deliberate breath. In through your nose, slow and full, all the way to the bottom of your lungs. Feel your diaphragm drop. Notice the brief pause before the exhale wants to begin. Then let it out completely – and find the quiet at the bottom before the next one starts.
That’s it. That’s the whole thing.
Not because it will fix anything, or because you needed something else to add to your day. Just because it’s been happening inside you, reliably and without complaint, this whole time… and it’s worth noticing at least once.
Last Gasp
“I took a deep breath and listened to the old brag of my heart: I am, I am, I am.”
— Sylvia Plath, The Bell Jar
P.S. There’s a lot more where this came from: unboring science, a weekly practice to try, and usually something that makes you think. The Full Exhale newsletter goes deeper every week, and it’s free. Subscribe here.