Dad died of lung cancer at 55. I saw him fight it for 3 years, as the cancer slowly killed him.
I had other family members that still smoked, and I would just shake my head with wonderment as they were seeing the same thing I was seeing. I knew that it had to be a powerful drug as everybody who did it had a hard time stopping even though they hated doing it.
The best way to stop, was to never start.