I kind of look at it this way: when I was getting fat I didn't eat horribly and fail to exercise every
day. There was the odd day here and there when I managed to eat a salad or take a bike ride. However, since I was on a strict "eat all I can get my hands on and sit all day" lifestyle, those days didn't keep me from gaining weight.
Conversely, now that I am on my new, healther lifestyle I figure that a few days in the other direction won't have an impact on my long-term progress. I just have to make it very clear to myself of which track I'm on and that just because I am eating X today or skipping Y, it doesn't mean that I don't have the same responsibilies to myself tomorrow.
Good job and getting back into the swing so quickly!