1. Eat only one of anything 'bad'.
2. Refuse to feel guilt about what you eat or drink - ever. Just eat it, enjoy it, forget it, move on.
3. Say thank you every day of the holiday - for something.
4. Whenever you want to murder the person in front of you, remind yourself of just one thing that they've done to help you out when you needed it. [If you can't think of anything why are they there?]