The trouble is that most of us have forgotten the right way to do it. Tai Chi teacher Sean Gibbins explains: "Look at a baby sleeping and you'll see its stomach gently rise and fall as it breathes from the abdomen. We need to re-learn what we once knew instinctively as children."
Tension and the frenetic pace of modern life combine to alter our breathing, encouraging a fast and shallow pattern which uses only the top half of our lungs instead of their full capacity. Yet good breathing, full and regular, is a cornerstone of any health regime, especially one designed to reduce stress, and is an integral part of holistic Eastern disciplines such as yoga, Chi Kung and Tai Chi.
Advocates of better breath control say proper breathing brings measurable health benefits including stronger lungs and lower blood pressure. It also promotes energy, confidence and calm. For teachers, with an ever-increasing workload, this has to be an essential self-help remedy.
One classic response to stress and anxiety is hyperventilation, when the average rate of 8-12 breaths a minute leaps to twice that figure as the body gears up for fight or flight. Early signs are dizziness and pins and needles, and the condition can cause wide-ranging health problems, from migraine to fatigue and depression.
Liz Whittington, a specialist in respiratory complaints, has seen a rise in the number of sufferers, many of them women juggling careers and families. "Breathing too fast expels too much carbon dioxide, which our bodies need to get oxygen from the lungs into the bloodstream," she explains.
It's a vicious circle: Low carbon dioxide levels trigger an alert in the brain's respiratory centre. This responds by setting its breathing "thermostat" to work with even lower levels of carbon dioxide. "That makes people feel even more short of breath, almost as if they're suffocating, and there is a lot of yawning and sighing in an attempt to draw in extra air," says Liz.
If all this sounds horribly familiar, a course of breathing lessons could help you cope more effectively under pressure. One option is Chi Kung, which roughly translates from the Chinese as "energy work". It has its roots in the ancient martial arts of China, and combines breathing exercises with posture, balance and a greater self-awareness of body and mind. Instructor Sue Weston has found that teachers find particular benefits from learning to inhale and exhale the right way: as their breathing improves, so does their relationship with pupils.
"Teaching is a very physical act, and by becoming easier in their breathing, calmer in their mind and more confident in their own body, teachers' attitudes to their class change, " she says. "At a subtle level, they become more grounded, and relaxed. "
Breathing deeply, "from the belly not the mouth and throat", also helps teachers project their voices across crowded classrooms, instead of shouting. "If you are confident in what you are saying and the way you say it, people will want to listen," says Sue.
Drama teacher Jo Street is a voice coach for professional actors and a specialist in presentation skills. She believes powerful breathing is as crucial in the classroom as on stage or before a TV camera. "Breathing is the key to both mental and physical control of your voice and your nerves," she says. You need to be standing correctly - feet slightly apart, with a straight spine and no tension. Then you emanate a positive approach which gives you an effective form of authority, without being authoritarian.
The process has a calming yet energising knock-on effect, she maintains. More oxygen goes to the brain, allowing you to think and express yourself more clearly. Gabbling or stammering are replaced by measured tones.
Singing teacher Linda Murray draws on the strength of pelvic breathing combined with Gestalt therapy to help her pupils - non-performers as well as professionals - to find their true voices. Most people who believe they can't sing or would like to improve their speaking voice are simply blocked by stress, muscle tension and the habit of hanging on to that vital outward breath, she says. "You put away tension, breathe in, then let go fully. It's a circular process, active and passive, like the cycle of the seasons."
To learn the right way to breathe you need a qualified tutor, and if you have chest or blood pressure problems, you should check first with your GP. Aim to be aware of your breathing throughout the working day. If you notice it speeding up, make a conscious effort to take slower, regular breaths, through the nose, but don't try to increase the volume.
If you're feeling stressed, try to find a quiet space and let go for a few minutes, breathing gently and calming the mind. Breathe through the nose to warm the air and filter out dust and bacteria. And remember to breathe out fully, concentrati ng on letting go of outward breath slowly, then letting the inward breath come in at your natural pace, without any forcing.
When we inhale we take in air containing oxygen and a tiny amount of carbon dioxide (less than 1 per cent) down the pharynx (rear of the throat), the larynx (around the region of the Adam's Apple) and the windpipe, on through the bronchial tubes and into our lungs. Here the air enters around 600 million air sacs, surrounded by equally tiny blood vessels. Oxygen, aided by the carbon dioxide, flows into the bloodstream, via the heart, to supply the body's vital organs and tissues.
When we exhale, we expel the waste carbon dioxide and stale air from the lungs. The entire process has taken just a few seconds and is repeated some 23,000 times every day.
When stressed, you breathe fast and shallow. As you push out more carbon dioxide and tension restricts the chest, you become more breathless. The heart speeds up from 70-80 beats a minute to 100. Agitation and shortness of breath make it harder to think clearly.
If you are happy and relaxed, your breathing is regular, gentle and quiet.There is no tension in the upper body, leaving space for fuller breathing.When you fall asleep, the body takes over and you breathe correctly, from the abdomen.
That's a state that stressed teachers should seek to replicate in their waking hours. Remember the yoga proverb: "Life is in the breath. Therefore he who only half-breathes, half-lives."
Chi Kung Sue Weston is at The Health Club, Administration, 8 St John's Court, Isleworth, Middlesex TW7 6PA. Tel: 0181 758 1996. For Chi Kung teachers in the North, Scotland, Wales and Ireland, contact the Tse Qigong Centre. Tel: 0161 929 4485
Tai Chi For registered teachers, send a stamped addressed envelope to the British Council for Chinese Martial Arts, 110 Frensham Drive, Nuneaton,Warwicks CV10 9QL.
Tel: 01203 394642
Yoga Most local authorities have classes. Details from the British Wheel of Yoga , 1 Hamilton Place, Boston Road, Sleaford, Lincs NG34 7ES .
Tel: 01529 306851
The London Academy of Music and Dramatic Art has details of voice and breathing teachers. 226 Cromwell Road, London SW5 0SR . Tel: 0171 373 9883
For a chartered physiotherapist, see your GP