An ex-girlfriend of mine had several dogs, and her mother installed a fancy invisible fence. Instead of the usual single shock, it would keep shocking the dog for 20 feet past the edge of the yard.
The point, I was told, is that the dog thinks the shocking will never stop unless it returns to the yard.
Sometimes I think quitting smoking is like that. It’s more than a single act, and it feels like it’s never going to end. But it does, of course. And for me, it seems to have. And now the only way I’ll be shocked again is if I cross back into that (metaphorical) yard.