What Are The Symptoms Of Lung Cancer?

I am 53 years old. General good health. I walk a few miles a day -- most days I will walk at least 10k steps. Need to lose some weight but not obese. I seem to feel the need to take a deep breath. Like my lungs don t feel completely expanded. Cough a little -- once or twice a day. I have pretty much convinced myself I have lung cancer. I am not a smoker. How likely is lung cancer in someone my age?