Close your eyes. Turn your attention to your breath as it flows in and out. If your attention wanders, turn it gently back to your breath. Keep doing that. You are doing mindfulness.

With practice, this simple technique (there are many variants) will quieten the nagging voice in your head, which tends to amplify the stresses and worries of your everyday life. My Year of Living Mindfully, which starts on Sunday at 15:00 and is available for a week, is an insightful documentary, not so much about how you practise mindfulness as about the mindfulness phenomenon.

An Australian television journalist called Shannon Harvey decided she would practise mindfulness meditation for 365 days, which sounds like one of those corny self-challenges of the “visit every pub in England” variety. In fact, it proves a useful framework upon which to hang an exploration of the science, philosophy and even commerce surrounding this modern, secularised version of an ancient Buddhist meditative practice. So while we see Shannon practising her meditation, listening to an app on a pair of giant white headphones in bathrooms, hairdressers, busy streets and aircraft, we are also given a huge range of interviews with experts and practitioners.

Shannon is both a thoughtful researcher and a personable interviewer and presenter. She starts with some startling statistics about the epidemic of mental health difficulties, with depression set to replace heart disease as the world’s biggest health problem by 2030, and notes the paucity of simple preventative advice. Then she goes looking for some treatment, or at least, therapy, that would be free or low-cost, available to anyone whatever their level of education and be scientifically recognised. Mindfulness meditation seems to fit the bill.

Inevitably, Shannon has a personal interest in the research: thirteen years ago, at just 24, she was diagnosed with the auto-immune disease lupus and has spent a fortune on treatments, some of them bogus, intended to manage the symptoms, which include chronic insomnia. Would mindfulness be any more successful?

So she sets off on her journey, starting with 20 minutes daily on the app (called Ten Percent Happier, though many are available) and building up. Along the way, myths are dispelled. Mindfulness is not a way of relaxing; it may have been overly hyped by big corporations; it is not even particularly enjoyable. At around Day 36, Shannon announces that the voice in her head is making meditation impossible. “I’m hating it,” she says. Then, a couple of days later, on a plane journey, she experiences a brief moment of total peace, and it all begins to make sense.

I won’t go into the conclusions Shannon draws as her journey reaches its end, after a silent retreat and a visit to a refugee camp in Jordan. Suffice to say, they are as thoughtful and honest as the rest of the film has been.

Over the last few years, mindfulness has been touted as the answer to many of the problems of daily life. Around the world, it has been a business trend, embraced by everyone from Apple and Google to KPMG and Procter & Gamble. In Britain, it has been used by Transport for London – 600 people have used a mindfulness-based stress reduction programme – and the London Fire Brigade. It is used by executives to reduce the stress on future goals and to enhance the sense of being in the moment. You can breathe, you can lie down and do a “body scan”, or you can spend several minutes contemplating a raisin. You can use an app or a website – take a look at headspace.com – you can join a group, find a teacher, or you can have an expert come and address your entire workforce.

Give it a try: it costs next to nothing and it may do wonders for you. Or, sadly, you may just find it very, very boring.

My Year of Living Mindfully is available for one week from Sunday 21 June at 15:00. Details here: https://ciff.shift72.com/film/my-year-of-living-mindfully/