Hello Nina! I follow BodyRock too, that's where I know you from. I do all the workouts and everything but I never write to the site, so you probably have no idea that I exist. But the weird thing is I have been reading your comments and seeing your process (even in your personal life) and so on. (Weird isn't it?) :)
Well to come to the point, I know exactly how this is, THIS is what I'm struggling as well, and it is like a never ending chain reaction, if you start eating bad, you can't find energy to exercise and when you don't exercise, you get so angry and frustrated at yourself so you find yourself eating bad again! You say: Oh crap, whatever I'll take that bag of cookies in me, I'm worthless anyway, look at me I couldn't even exercise today! That's how it goes for me sometimes. And I feel really reaallly I mean REALLY disappointed at myself, being very harsh at myself and punish myself after these kind of events. I start making promises with myself and saying "Okay, tomorrow I'll be a really good girl etc." AND it becomes WORSE! The only thing I can say to you is what my boyfriend says to me: You are setting your goals too high, and when you can't find time/energy or etc. You feel like a loser. Don't do that, especially when you are trying to come back to your old routine, or have some special occasion (like extra work hours etc.) just take small steps. When you try to jump into it with full throttle, it just pushes you back.
These were the exact words that my boyfriend told me, and it really helped me. I still do some slacking/eat wrong sometimes but then I try not to punish myself or care about it so much, it was a mistake I did, but I don't care I'm aweasome anyway. Then I find myself pushed from the bed and doing ridiculous amounts of zuzana workouts :) Sometimes our minds and consciouses are our worst enemy.

Hope this helps!
Hugs
Ayca

ps. I sent this comment twice, because I'm not sure if I was able to send it (No skills in czech :)))) )