I only ever smoked in a social setting. I could always go without for days on end, but then when others smoked it set me off. For me, i started smoking marijuana which got me into cigarettes, rolling up a joint with tobacco made me want to smoke tobacco alone eventually.
Now though i don't smoke anything, but i found after a few days of not smoking, that first cigarette gave me a nicotine rush and a feeling of calm.
Paul