Are you breathing slowly and smoothly through your nose? Or are you breathing short and choppy through your mouth?

The difference sounds subtle, almost inconsequential. But an emerging body of research tells us that how we breathe has a profound impact on how we think and feel. Good breathing cultivates resilience, focus, and productivity. Bad breathing cultivates stress, anxiety, and a scattered mind. 

Just consider mouth breathing. If you're like most people, you likely fall into this habit from time to time, either during the day or when you're asleep. But how bad could this habit really be? 

To answer this question, James Nestor, author of the recently released book Breath, engaged in a breath-style reenactment of the classic documentary Super Size Me. Instead of eating Big Macs and fries three meals a day for 10 days and nights, Nestor forced himself to mouth breathe. He jammed earplugs into his nostrils and closed them shut with surgical tape.

The results confirmed what scientists have been saying for years. After just a few days of mouth breathing, Nestor's snoring at night had increased by over 1,000 percent. His blood pressure spiked by an average of 13 points, putting him in a state of stage one hypertension. And, not surprisingly, he felt anxious, scattered, and "awful."

Nestor's masochistic mouth-breathing experiment shows two things. First, it shows that bad breathing leads to all sorts of bigger problems: anxiety, insomnia, high blood pressure, and other chronic health conditions. 

Second, it shows that small changes in the way we breathe can produce radical results. It shows, in other words, that we might not need more and better supplements, expensive wearables, or any of the other elaborate tools we often use to attain peak performance.

It might be that all we need to experience less stress and greater resilience is a simple technology, one that's always free and always available: our breath.

How can we breathe better to experience these benefits? Consider three techniques.

1. Nasal breathing.

If Nestor's experiment and the volumes of scientific evidence on the dangers of mouth breathing teach us anything, it is this: Breathe through your nose. During the day, when we are awake and aware, this habit is relatively easy to develop. Just pay closer attention to how you are breathing. During the night, however, things get more complicated. We lose consciousness of our breath and really everything else. We are, after all, asleep.

How can you stop mouth breathing when you're sound asleep? Mouth taping. That's right, it sounds totally crazy. But all you have to do to improve your sleep quality and break this bad habit is place a small square of tape over your lips in the middle of your mouth. 

2. Lengthen the breath.

Another surprising insight drawn from the research on breathing is that, just as we have a tendency to over-eat, we tend to over-breathe. When experiencing stress, irritation, or anxiety, in other words, our natural impulse is to speed up the rate of our breathing and breathe more. 

The problem is that this instinct makes our stress, irritation, or anxiety worse, not better. The more we breathe, the more we begin to dump CO2 from our blood stream, which in turn disrupts the delicate balance of oxygen and CO2. The result is that we get less blood flow to the brain, while also activating the body's fight or flight response. Put simply, the more we breathe, the worse we feel. 

The easy antidote is to make a conscious effort to slow down your breath and, as crazy as it might sound, to breathe less.

3. Breathe in a relaxed way. 

Tell someone to take a few deep breaths and they'll often breathe with such intensity that it sounds like they're about to summit a mountain or get several shots in their arm at the doctor's office. This is yet another bad modern habit of breathing. We approach breathing like running a race or deadlifting several hundred pounds. We put way too much force into it.

A better alternative is to breathe in a more relaxed way. Use each exhale to soften your breath. Make it smooth and effortless. Make it so soft and subtle that you can barely even hear it. 

The great thing about these three techniques is that you can do them anytime, anywhere. They don't require expensive equipment. They just require that you catch yourself each time you fall into your old habits and shift back to a better way of breathing.