We've been doing it for as long as we've existed. But according to journalist and author James Nestor, we could be doing it a lot better. The average adult takes around 20,000 breaths every day, but according to Nestor, we take most of them through our mouths rather than through our noses, leading to all manner of problems from excessive snoring to asthma. Nestor is the best-selling author of "Breath: The New Science of a Lost Art", which has just been translated into French under the title "Respirer". He joined us for Perspective.