You breathe around twenty thousand times a day. That is not a metaphor, it is a number. And according to Ruben Sosa, founder of the Respira Institute, it is the only thing you do that often without ever once checking whether you are doing it properly.

His comparison is that breathing is a remote control for the nervous system. Depending on the pattern - faster, slower, intense or subtle - you shift the body from one state into another. That is it. No app, no subscription, no specialist to pay.

What he warns does not work is fast breathing. In his view it multiplies the sensations of stress and can worsen hypertension. Chronically accelerated breathing goes hand in hand with a permanently activated nervous system and a tension that never comes down.

The method he proposes is called slow, subtle, diaphragmatic. Slow sends a safety signal to the brain. Subtle means more air is not better oxygenation - the key is the carbon dioxide balance, which is the opposite of what most people think. Diaphragmatic means using the main breathing muscle instead of lifting your shoulders.

He singles out three techniques specifically. The physiological sigh: a double inhale through the nose, then a slow exhale, five times when stress is high. Humming: lips closed and an "mmmm" sound while exhaling, five to ten times, calms the mind. And the evening pattern before sleep: three seconds in, four seconds hold, five seconds out, without filling all the way up.

The rule he keeps repeating is breathing through the nose, always. The nose filters, warms and humidifies the air and produces nitric oxide. The mouth, as he puts it, belongs to the digestive system, not to breathing.

The diaphragm is not only there for air - it affects posture, the spine, and venous and lymphatic flow. Which is why his point is not to sit down for ten minutes a day and practise, but that functional breathing across the whole day counts for more than an occasional exercise.

The health and wellness industry sells you belts, apps and watches that measure your stress. This does not sell, which is why you rarely hear about it. An old yogic line says life is measured not in years but in breaths - a fine sentence, and also the only free thing in the whole story.