Traveling can definitely throw a wrench into one's health/nutrition/fitness routines, in fact routines tend to go out the window when dealing with changing situations. This is especially true when a) your travels include flying to your destination and you don't have the car to toss anything and everything into, b) changing time zones (jet lag seems to be a valid excuse for anyone no matter the direction traveled), and c) trying to squeeze in as many activities (work or play) into the day as possible. Plus, people often prescribe to the "I'm on vacation, and I deserve to relax and splurge."
While I do not disagree with this statement, my thoughts are that we all deserve to be healthy and vibrant, too, especially when on vacation or traveling for business. These times can be draining, and maintaining a nutritious diet (which does not necessitate deprivation) and maximizing physical activity are two ways to keep your energy levels buzzing to make the most of your trip! Of course, you know this if you include a healthful diet and exercise program in your day-to-day life--that why you do it!
In my experience it's might be better to loosen up, relinquish some "rules," and simply resolve to getting back on track once home. I know that I've found myself in the position of being on vacation and stressing over when I'm going to fit in a run or will there be something on the menu that jives with my dietary preferences and considerations? I worry about getting home after being gone for a week and losing all of the fitness that I've worked so hard to build. After all, I'm getting so old--my body doesn't adapt the way it did 10 years ago when I was playing college soccer! I'm getting better about these rules, but nutrition and fitness are values close to my heart and a large part of who I am, which I cannot leave at home; those values travel with me, but I can be flexible.
Instead of obsessing, make healthy choices when you can. Utilize the fitness center in your hotel, go for a run/walk outside to explore the place you're visiting, hike the stairs to your hotel room, don't skip meals, shoot for balance: lean meats, fish if you're on a coast, lots of greens/veggies, and be prepared with healthful snacks like nuts, fruit, hard boiled eggs, string cheese. These all travel well, and the proper combination will fuel you for whatever your travel itinerary may be. Most importantly, just because you're traveling and perhaps feel a bit out on sync, you can choose how to mitigate the situation to make the most of your trip and your health!