Recognize that missteps are necessary.
Nobody runs a perfect diet. Occasional missteps always happen, and should be understood as a natural part of the process. You’re trying to minimize them, yes, but you don’t need to get too upset when one happens. Whether it’s chowing down on fast food today because you were too lazy to cook yesterday night, a holiday meal, or simply because you want to eat a comfort food that may not quite fit into your dietary plans, they’re not going to instantly sabotage all your hard work (and if they could, it clearly wouldn’t have been very hard work in the first place!). Recognize that these things happen, even to the best of us, and don’t get obsessed over it.
Stay on the grind.
A common attitude I see is something like “oh well, since there’s gonna be a lot of parties and holidays over the course of the month, I might as well just take it off anyway.” The whole point of fitness is that it’s a lifestyle, not just something you do every now and then. Inevitably, this leads to lots and lots of new years resolution types: “since I skipped December, I’ll just get serious again in January and go from there.” Of course, the vast majority of these people fall out rather quickly, because they’ve now made it harder for themselves.
You won’t be able to stick to your plan perfectly during holiday season, and this is a given. You’re going to be tempted by lots of food, and you’re going to have less time to get to the gym or be less motivated to even go. But! The emphasis should be on consistency, and that means something, even if it isn’t perfect, is always better than nothing. Whatever you do, don’t stop.
There’s a saying that if you’ve got a plan, even if it’s an awful one, then everything is better because it’s all going according to plan. This may mean eating less in the days leading up to a party, or spending more time in the gym in anticipation of not being able to for the next week. Whatever it is, have a plan. When you have a plan, everything turns out better, even if that plan isn’t perfect or isn’t perfectly adhered to. Make a quick sketch of your holiday season and write down some notes on a calendar about what to do each day, as this will go a long way.
Portion control, portion control.
Portion control is half the battle. Since holiday foods tend to be traditional stuff like turkey or ham, you probably don’t have to worry about food quality unless your sweet potatoes are more marshmallow than potato. Simply restricting your overall calories is all you need to ensure that your weight remains stable. Imagine the amount you were planning on taking, and then take less. I could reel off all the portion control tricks in the book, but I’m sure you’ve heard of most of them by now. Eat slowly and don’t stuff yourself.
Be okay without control.
Above all, you need to be okay with the fact that you aren’t going to have perfect control over your situation. Oddly enough, I usually lose weight during the holidays because my body is used to a high-calorie diet and when I’m being fed by relatives for a week I have less ability to graze constantly and stuff my face. For me, that’s a big setback. But ultimately, you’ve got to be okay with the fact that your diet is going to be in the hands of other people than yourself. If you aren’t, you’re just going to get anxious and sabotage more of your hard work than if you keep a cool head.