I think an important part of traveling is remembering to take care of yourself. On my trip across the country last year I forgot about that and let myself go a little. A few pounds later I realized I probably should have laid off the gas station snacks.
But more importantly, you need to stay active. Especially if you're on the road putting a lot of hours behind the wheel. I'd say it was pretty easy to do on our Oregon-California road trip considering it was meant to be a surf tour of the west coast. Thankfully we had our own resident yogi to keep us in check and do a couple sun salutations on the beach too. But aside from surfing and a couple downward dogs, we also did a couple morning beach runs and, of course, a little ATV action [which gave me the work out of my life. I think the shock that overcame my body helped me burn at least 5,000 calories. I wouldn't recommend it.]
I honestly cannot stress more about the importance of staying fit when you travel. Because trust me.. I have been there.. and getting home from a trip feeling like an overpacked sausage is not fun. And I can comfortably say that this past trip didn't leave me feeling like I should go on one of those ridiculous juice cleanses [even though we may have had an excess amount of brie and peanut butter throughout the trip.]
Don't let yourself go and stay fit for the road!