I quit sometime in the mid 70s. I discovered way back then I could buy more Mopar race car parts with the money I was spending on smoking. Pretty much quit drinking booze at the same time, for the same reason. (That and it wasn't as much fun once I was legal age!)
I was doing a pack of smokes a day until I spent 4 days in the hospital for an unrelated reason. When I got out of the hospital I figured I had most of the habit kicked. There were still trying times, but I succeeded. The memories of racing provide more fondness then anything smoking or drinking related did. Gene