I took up smoking for a few months at a time on trips when I had traveling companions who smoked. Liked it. Sitting in an outdoor cafe in Vietnam, sipping on a coffee, smoking and talking. The nicotine didn't seem to do much but the ritual of smoking in itself was surprisingly enjoyable.
But getting home to the crew at work and witnessing them desperately trying to stop put an end to it. Hard on the pocketbook, tough on the skin (wrinkles), lungs, circulation in the fingers, almost everything.
Some smokers seem to have immunity. My grandfather was an engineer who chain smoked every day on the job. Lived to his mid 80's, no ill effects I was aware of.