I know the feeling! I'm freezing and tired, and this healthy salad without dressing is just not doing it for me, when all I want is a big bag of chip shop chips!
The only thing that will keep you going is will power. Remember why you started dieting and keep your goal in mind. Give yourself a reward for every time you get through a day or a week without letting the cravings beat you - it doesn't have to be very big. A magazine, a nice bubble bath or a new lipstick. Weighing yourself once a week (and no more than once a week) will help keep your goal at the forefront of your mind.
If the cravings get really bad, try something else. Have a piece of fruit or something that is allowed on your diet and then wait an hour to see if you really wanted what you were craving in the first place, or if you were just hungry and going for familiarity. Excersise helps. Go for a walk or dance around to your iPod - anything that gets the blood flowing.
And never forget that a LITTLE bit of what you fancy does you good. If, for example, I'm cooking chips for my partner's dinner, I have one or two, just to get the taste in my mouth and not feel deprived. Have a square of chocolate once in a while. You'll do better if you think you CAN have something but you CHOSE not too.
Just remember it will all be worth it in the end. I've only been going for three weeks, but I've lost 9.5lbs. It can be done, you just have to believe that you can do it. I'm getting weighed tonight so we'll see how I did this week. Wish me luck and good luck to you. You can do it!