That’s a good question, why would anyone do it? I guess to get healthy and fit would be a reason to do it. Some people do it to look good or competition. I wonder ( with the exception of critically ill people) if everyone in the USA was healthy how much it would hurt the medical and pharmaceutical industry and save people so much money. Most people don’t realize after 30 their muscles stay to deteriorate and weaken. Your heart, diaphragm, back and rib are muscle and they weaken too the older you get, diet and exercise is the best and easiest way to strengthen them. I’m not saying it will help you live long but I don’t think it will make you live less. There is so many illness and pain that can be helped just eating healthy and exercise. It’s so easy to do if you will get in a routine, I spend 15 minutes exercising most days and up to 30 minutes walking or running. That is a small price to pay to be healthy, fit and feel great!