Just dont take any cash to work, that way you cant buy any fags.
I'm lucky I just stopped a few years ago, nextdoor neighbour said once a smoker always a smoker & didnt belive somebody could just quit like that....so I did just like that on a wednesday evening & haven't been bothered by not smoking from that time onwards.
I've given up before, just stopped one day and that was that. I have immense willpower. But then, I'm not really much of a smoker, I can take it or leave it, I only do it because I get bored.