Travel fitness is an important niche which I am paying attention to this year. The problem with travel is that it brings you face to face with extreme conditions and junk food. I do not really recommend going to gymnasium and pump up your muscles with those heavy iron. However I do advise spending at least an hour doing some basic exercises. This blog section on fitness would have every tips and tricks related to to being fit while traveling.
Remember, you don’t need to be “all or nothing” — you just need to be good enough. And every decision helps!