Michael, a 51-year-old business owner, was a one-pack-a-day cigarette smoker for 30 years who quit in 2017. As someone who enjoyed good health, Michael never worried about his lungs. However, chronic shoulder pain that he attributed to over-exercising and weightlifting began to bother him. On a whim, Michael Googled "causes of shoulder pain" and was surprised when lung cancer came up in the search result.