Don't sweat it... if everyone gave up after a day of losing control, nobody would get anywhere :-)
I try to stay on the low end of my calorie range (1200) throughout the week, and then give myself one day on the weekend when I am not as hard on myself. Granted, I try to not OVER indulge, but it's nice to look forward to.
The more I stay on the low end of my calorie range, the less I WANT to eat on my "cheat" day.
You can do it! Just stay focused on your goal :-)