I was a radical anti-smoker all through middle school and high school, but that all changed when I went into the Marines. While in infantry training, there were packs of cigs, menthols, in the c-rations (field food). I had mild allergies to the dusty Camp Pendleton environment. One sneeze and a D.I. kicked me, yelling how that would get me and everyone else killed in combat (all too true). Further, beyond comprehension, non-smokers were penalized during boot camp. When the D.I.s allowed smokers to have a cig, the non-smokers had to do pushups while the others smoked. So, I began falling out with the smokers, and sneaking a cig here and there, and the menthol seemed to quell my sneezing.
Addiction begins with a whimper, not a bang. One thing led to another and by the time I was out in the fleet, I'd progressed to a heavy smoker--a pack to a pack and a half a day. Forty years later, I've had all the fun I can stand from cigs.