I've fallen off the wagon many times! It's taken me over a year to get where I am. If I didn't fall off so many times I'd probably be at goal by now.
The important part is getting back up and going again. Never letting yourself fall all the way back.
The way I stop myself from completely going off is by allowing myself to eat more carbs and OWL appropriate foods. I've done induction on and off for so long I needed that change. I also allow myself one cheat meal every two weeks. Now that I have that meal to look forward to it helps me keep focused until then. But not everyone can do that, I know I've had times where I've abused the cheat meal by turning it into a whole day of bad food.
Just keep going and do what you can! You will get their more slowly if you keep going back to old habits, but you will get there eventually as long as you focus on healthy eating. Eventually it will become habit and you won't want to cheat as much