The curious ways of a smoker

I have nothing against smoking, as long as you don��t do it in my space, but why is it that in spite of having a hacking cough and bringing up all kinds of gunk with it, a smoker just has to have that 5 minute break from his/her work station to huddle , in the freezing cold, by the office back door to have yet another cigarette? Never quite been able to understand that.