This has been an issue at a number of barns I've been at as well.
One barn was particularly bad. We were constantly having issues with the Mexican men that lived on the property to clean stalls and such (not sure what to call them, as they weren't really grooms or ranch hands... stable hands?)
Not only did we have a hard time trying to get them not to smoke inside or near the barns, we were always finding cigarette butts in the grassy areas where we'd graze our horses. NOT GOOD!
I ended up leaving that place for a number of reasons, the smoking issues being one of them, and I, myself, was a smoker at that time.
I, too, quit cold turkey. For me, using a change of environment really helps me break bad habits. With smoking, I was moving to another city, new apartment, new barn, new social circle, new everything. I knew I'd been wanting to quit, so I used that as my opportunity. Smoked my last 'grit just before getting in the car to head out on the road, the day I moved, and never smoked another. Jolly Ranchers were my best friends for a few weeks. Now, I'm totally repulsed by even the smell, I have no desire to taste another cigarette, as long as I live. I think my addiction was more about the habit of smoking that I had gotten into, as it seems like I had an easier time quitting than other people I know. Now, I'm totally repulsed by the smell and have zero desire to ever taste another cigarette.