@MattWSpanjer,
I lost my dad to lung cancer - and he quit, but unfortunately it was too late.
Not to mention besides lung cancer, your risks of these cancer increase dramatically - including cancers of the lung, esophagus, larynx (voice box), mouth, throat, kidney, bladder, pancreas, stomach, and cervix. Besides cancer these other health risks - heart disease, stroke, fertility, tooth loss, cateracts, diabetes, arthritis, immunity - basically smoking negatively impacts every part of the body. According to the CDC is it the number 1 preventable cause of death in the US. I think my doctor had a tad bit of validity in mentioning not smoking as a guarantee to increasing your life and quality of life.
Aside from the health benefits - if you don't smoke your breathe smells better, you smell better - and cleaner, your skin doesn't age as quickly so overall not smoking you look better and smell a heck of lot better.