Both ethics and health benefits are what interested me to adopt the vegan lifestyle. There were times where I suffered from throat and chest pains. A build-up of phlegm that lead to severe coughs and chest pains would attack me each week. I did not have asthma though.
Before going vegan, animal protein was a part of my diet. As I began to transition to a vegan diet in early 2015, the attacks became less severe and rare. I've been vegan for 7 months and have yet to experience an attack since mid-2015.
After going vegan, I began to do more research so that I could learn more about veganism. This lifestyle not only benefits me, but also the animals and the planet. Animal agriculture is a business. Cancer(s) and heart disease are also a business. The sicker we are (as a people), the more the industry profits. It makes sense to try to be healthy, but it doesn't make dollars for the industry. My only regret about going vegan is not doing it sooner.