I usually struggle to maintain my habits while traveling, mostly because I give myself permission not to, when it doesn't have to be this way. Just because I don't have my meals from my subscription plan doesn't mean I should eat anything I want. Just because I don't have a treadmill in my office doesn't mean I can't use the treadmill at the hotel gym.
Things don't have to be exactly as they are, but the options available to me can serve the same purpose (eat healthy, move more, improve sleep, etc). Travel presents me with opportunities I should make the most use of, such as networking with others when attending conferences, like the Seedstars Global Summit I'm currently attending in Lausanne, Switzerland. But it's not a matter of either/or in most situations.
I can exercise AND network AND meditate AND explore the city.
As long as I try to remain calm (and not to stress out or panic) and manage my energy, I can make the most of my days. And just because I'm traveling doesn't mean I get to abandon my writings. If anything, I want to spend some solitary time catching up with my writing.
I should be clear about my goals and flexible about my approach towards them, while trying to make as much progress as possible.