As a former smoker, I can tell you it's much easier to say, "I'm going to quit!!" after you've just smoked a cigarette. The reason for that is that you've got that drug in your system - you feel strong. You feel like you'll never need it again. And then in a few hours, or whenever you'd normally smoke again, you get that itch....the feeling is so powerful that you think, "What the hell was I thinking? I can't do this! Why did I want to do this? I don't wanna!!!"
Although it's possible to get through that feeling (I'm living proof of that, over here!), it's much easier to make that decision and stick with it after you haven't smoked for a while. You think, "I have gone this long without it, why do I need it, really?" I've had several people go about it this way after being ill and it's worked well for them.
The same can be true about making the decision to get fit. It's incredibly easy to say, "I'm going to stop the binges! I'm going to eat healthy! I'm going to go to the gym!" right after you've overeaten or been on a binge. But when it comes time to actually stick to it, it's not always as easy.
If you make your goals at the right time, you're more apt to stick to them. I try to avoid setting a sky-high goal after a negative experience with food. Those are the times to set smaller, more attainable goals. Get your legs under you and then jump for the stars!