I am impressed when I see people who are still disciplined with what they eat and continue working out despite the fact the holidays are upon us. They will have less de-conditioning and weight gain to deal with at the first of the year.
Don't give up on healthy habits just because you have several Christmas parties and junk food surrounding you for the next couple weeks. You can still eat reasonable amounts of holiday food and maintain your weight. The problem is when people give up and decide to binge eat from Halloween until New Years Eve, saying they are going to get serious and get in shape at the first of the year.
Finish the year strong and you will be far ahead of everyone else who is going to be starting from scratch again at the beginning of the year. You still have 15 days days to work towards what you wanted to accomplish in 2009!