You'll be surprised sometimes, I had a lot of dessert items around Thanksgiving and somehow still lost weight that week, I also slacked on the excercising so that's what surprises me.
For me, the number 1 thing to worry about is your state of mind, always think thoughts that keep you moving forward, like if you indulge a bit, don't think, oh great, I just messed it all up, just say whatever, I'll just burn it off.
Like for me right now, my initial goal was 60lbs, I hit that, I need to lose another 30, but instead of thinking just in terms of that 30, I think about it as 90 overall and that I'm 2/3 there rather than not started cutting into the 30, keeps me more confident and progressing forward to focus on what I have done rather than look ahead at what I haven't.
Last spring, I think it was Ski, said it would probably take a year to lose what I was trying and I wanted to lose it by summer, I actually almost cried at the notion of taking a whole year to do it, it made me feel like I was fighting a battle I couldn't win. It's been a year, it took a year, and now I don't care, I fought and I won.