I was in a Pilates class the other day when my instructor suddenly stopped me and said: “You need to be breathing out of your diaphragm.” It’s something I’ve been told to do before in yoga or meditation classes, but have never quite been able to nail it. As all the pros say, though, diaphragmatic breathing can be incredibly helpful.

It differs from shallow or thoracic breathing because it’s all about drawing inhales through your nose and all the way down the stomach. As a result, it has a deeper effect. “When the diaphragm contracts and moves lower, the chest cavity enlarges, reducing the pressure inside the lungs,” says Payel Gupta, MD, a New York City-based allergist and immunologist. “It allows us to inhale and take a deeper breath in. When we take a deep breath, we use our diaphragm even more, and the diaphragm moves down further and allows more room for the lungs to expand and for more air to enter into our lungs.” As a result of breathing more conscientiously and deeply, more oxygen begins flowing throughout your body.

Because of this newfound air flow and slowing down of the breath, it has a soothing effect on your nerves. “There’s some thought that deep breathing is a way of interrupting the fight-or-flight response and triggering the body’s normal relaxation response,” says Dr. Gupta—hence why she points out that it’s particularly recommended and useful during a yoga practice, meditation, or simply when you’re stressed AF. Research has even proven that diaphragmatic breathing gets your mind and body relaxed because it helps to lower your cortisol levels.

“Deep breathing is a way of interrupting the fight-or-flight response and triggering the body’s normal relaxation response.” —Dr. Payal Gupta

Babies know how to breathe diaphragmatically—but we gradually move the breathe upwards as we grow up. “We’re born knowing how to use our diaphragms, but as we grow up, we start to forget,” says Sarah Villafranco, MD, physician and founder of Osmia Organics. “When babies first come into the world, you can see them pooching out their little bellies to take big, full breaths, which allows for the best gas exchange in the alveolar sacs of the lungs. As we grow up, we shift the work to the muscles of the chest and neck, in some cases even sucking the abdomen in when we inhale.”

The issue with breathing out of the chest and neck is that it creates more pressure in the muscles of the area. “This creates and maintains neck and shoulder tension and decreases the volume of each inhalation, because we’re not using the strong musculature of our diaphragm,” says Dr. Villafranco. Or in other words, you’re also not getting as much oxygen as you could.

What’s more, reverse belly breathing can confuse the body. “Typically when you’re not breathing with your diaphragm properly, you are breathing into your chest only, or reverse breathing where you are still using your diaphragm but in reverse (emptying your belly on the inhale and filling your belly on the exhale),” says Meghan Rolfs, instructor at YogaSix. “Breathing in reverse works against your body’s natural movements and can confuse your muscles. Breathing only from your chest draws the abdomen in and stops your diaphragm from lowering, so you’re only filling your upper chest with breath and mostly likely tensing your shoulders to compensate.”

That’s not all to say that you need to train yourself to do belly breathing constantly—it’s just a super useful (and easy!) tool to use in certain scenarios. “Taking deep breaths constantly is not required during the day, but it’s good when you need a relaxation response,” says Dr. Gupta. Or, say, when you’re struggling to get through a minute of chair pose in a yoga class—or during any workout, really.

“During a workout, sometimes people can be so involved in whatever physical activity they’re doing that they ‘forget to breathe,'” says Dr. Gupta. So true. “Regular reminders to breathe in and out during exercise is common practice during group workouts, and it also helps with muscle relaxation when you’re taking deep breaths.” When trainers tell the class to remember to breathe, they really mean it—for your own sake. “It can be harder to focus on generating your breath with your diaphragm during an intense workout, but the more you do so, the more oxygen you’re taking in and delivering to your muscles when they need it the most,” says Rolf.

Despite how beneficial diaphragmatic breathing is, though, I just find it very difficult to do. Like, when my Pilates teacher told me to do it, I didn’t really know how to go about doing so. Turns out it takes quite a bit of practice.”Taking breaths through your nose allows you to better activate your diaphragm,” says Dr. Gupta. “You can feel the air moving down when you take a deep breath in through your nose.”

Dr. Villafranco’s fave trick? “To practice the technique, I face my standing desk with both feet flat on the floor, my sternum lifted, and my abdomen touching the desk in front of me,” she says. “Then I inhale slowly, and focus on trying to push my belly into the desk as I breathe in, which pushes my body backwards a little bit. As I slowly exhale, I let my belly contract back towards my spine. And I make sure to notice and enjoy the sense of calm that washes gently over me with each breath.” Now just breathe.

For other ways to relax, check out the best way to de-stress according to your astrological sign. And here are 10 methods for how to de-stress at work.