Oximetry
When you are interested in the importance of good breathing, all you need to do is look at an oximetry reading of your own blood. Oximeters are able to verify the amount of oxygen in your blood by shooting a kind of laser through your finger, or other part, and then measuring the amound of bounce-back that your platelets give when they are loaded with oxygen. That will give you a percentage number that will let you know what level of oxygen you’re holding. The doctor might be able to tell that you smoke based on your reading, or he might ask why it’s so high. Possibly you’ve simply been jogging for a few years. This is how such things pay off. But people with respiratory problems that aren’t preventable might also get lower readings, depending on their condition, and this will be evident to the doctor. In fact, I think it might even be one of the tools that they use when making their diagnosis, because if you have something like asthma, your body might not be carting oxygen to the blood as well as in a healthy person. It’s just something to keep an eye on and some people might want to have an oximeter right in their home. They’re relatively inexpensive these days, so consider it.