i repeat my goals to myself over and over and then go grab some carrots. lol it works though and if that doesn't i look at pictures of my kids and think - i want to be the best role model i can be for them. and that stops it dead.
Once I started fueling my body better and more regularly, my cravings went away.
As far as the 30 mins of cardio goes.....I would work towards an hour. There is also the variable of what heart rate you are working at which is critical as to whether you are really training your body to be more efficient (ie. burn fat)