I have been travelling recently...and I ended up smoking especially when I am very free...of course I do drink too, so that contributes to the urge/habit to pick up a stick or 2 (or more, knowing myself). What I do find useful sometimes is, do a quick high impact workout(10 mins) and a deep yawn thereafter...that helps to simulate the inhalation "style" when I smoke and also stimulate the paralimbic system that helps to relax me and then quickly head off to bed