Take a deep breathing, slowly, in and out through your nose.

You are tapping into an internal mechanism for better health and fitness. It’s simple, it’s free and it’s always there.

Have you ever thought about your breathing? Most people don’t. Breathing is an automatic function of the body, but you can also control it. You must breathe to live and so your body will do everything it can to make that happen. But your environment, stress, and how you breathe can alter and even impede that process.

The good news is that simply practicing nasal breathing can turn it all around.

Taking slower, longer breaths in and out through your nose can help with everything from reducing anxiety to boosting athletic performance. Basically, nasal breathing slows your rate of breathing down, which means your body doesn’t have to work as hard to get oxygen into your bloodstream. This is great for overall health and athletic performance, according to a 2018 study in the International Journal of Kinesiology and Sports Science.

Changing your can feel overwhelming but starting with awareness and practicing tested methods can help. Nestor suggests inhaling for a count of five seconds and exhaling for five seconds to slow your breathing. Navy seals favor box breathing in which you inhale for four seconds, hold for four seconds, exhale for four seconds and hold for four seconds. It has a calming effect and helps to activate your parasympathetic nervous system, the rest and digest part of our nervous system.

“When we breathe correctly, we have a sufficient amount of carbon dioxide, and our is quiet, controlled, and rhythmic,” explains Patrick McKeown in The Oxygen Advantage: The Simple, Scientifically Proven Breathing Techniques for a Healthier, Slimmer, Faster and Fitter You. “If we are over-breathing, our breathing is heavy, more intense, and erratic, and we exhale too much carbon dioxide, leaving our body literally gasping for oxygen.”

The Wim Hof Method, which is a mix of breathing and cold therapy, has not only caught the attention of major media outlets and celebrities but has also been tested by science and determined that the training boosts your immunity.

“The present proof-of-principle study demonstrates that the sympathetic nervous system and immune system can be voluntarily influenced through practicing techniques that are relatively easy to learn within a short time frame,” write the researchers of a study published in the National Library of Medicine. “It, therefore, could have important implications for the treatment of a variety of conditions associated with excessive or persistent inflammation, especially auto-immune diseases.”

If you’re looking for an edge to your training or a way to simply feel less stressed, start noticing your breathing, and close your mouth.