One of the reasonably well known side effects of smoking pot is sometimes a feeling of intense paranoia. Well, over a period of a few months, I was regularly smoking pot in the evenings and convinced myself that smoking cigarettes would kill me and while stoned I was able to exaggerate these feelings to the point of paranoia (I was thinking very, very hard. Overthinking, another well known side effect).
Subsequently, even during the day when I wasn't high, I could still "feel" that paranoia whenever I lit up a cigarette.
It took maybe 2-3 months, but eventually I stopped smoking cigarettes all together, and even now almost 20 years later, just one drag starts to make me feel sick.
Of course, then I had a pot smoking problem, but that's a different story, which required a different solution.