I wrote this a few weeks ago... But:
Seriously, most smokers only take a deep breath when they are smoking. They become accostomed to taking a deep puff avery so often and that satisfies the need to do so. Shallow breathing does a poor job of transferring CO2 and replacing it with Oxygen.
It may seem like the opposite, but a smoker actually gets an urge to smoke when their CO2 levels are too high and their O2 levels are too low. They smoke because their body needs to take a few deep breaths.
Try this when you get the next urge. It is the same method used by mountain climbers and runners to force CO2 and O2 transfer.
Deep breath in. Hold it. Purse your lips like a whistle or a kiss and blow out slowly with some pressure... Like you are blowing up a balloon or blowing out candles.. Do that two or three times and the urge will pass. The deep breath brings in the Oxygen and opens the lungs, the pressure increases the rate of transfer.
Mark is smoke-free and healing for the last Four Months, Six Days, 15 Hours and 33 Minutes, while extending his life expectancy 11 Days and 4 Hours, by skipping 3216 smokes and saving at least $848.73.