Also, be sure to keep an eye out for Tommy John's upcoming infographic featuring some of the comfort tips I've included in this post! They specialize in men's base layers, like boxer-briefs, so comfort is in their DNA.
Quality footwear is one of the few pieces of gear I'm willing to splurge on. When you travel, you're often on your feet all day. Terrain can be uneven and unsuitable for cheap and uncomfortable footwear. This is especially true if you're traveling with a heavy backpack. I recommend buying a pair of hiking boots with rigid soles and ankle support. Trust me, you don't want to walk for hours on cobblestone streets and potholed sidewalks in a pair of loafers or high heels. Your feet and ankles will thank you at the end of the day.
A good night's sleep is essential to staying healthy on the road. If you're a budget traveler like me, you'll often find yourself sleeping on friends' couches, in airports or on cheap hostel beds. In China, where I currently live, even medium-range hotel rooms come with beds that are slightly firmer than particle board. If you travel with an air mattress, you'll set yourself up for a comfortable night's sleep no matter where you are. Technology for air mattresses has greatly improved in the last few years; you no longer need to carry a thin piece of foam that won't even fit in your backpack, or a huge bed that requires an air compressor to inflate. Nowadays, there are several models of air mattress that are the size of a 1-liter Nalgene bottle and weigh less than one kilo. They take less than a minute to inflate; you'll be in dreamland before you know it.
Ear Plugs and Eye Mask
It's 3 a.m. You're in a hostel dorm room, sound asleep. Suddenly, the door creeks open and the lights are turned on. You hear laughter and maybe even some sounds that you can't un-hear. Your bunk-mates have returned from a long night of drinking, and now you're wide awake. Of course, you would never be so discourteous, but not everyone will follow the basic rules of dorm-room decency. You could eschew dorms in favor of private rooms, but that can get quite expensive. What other options are there?
Use ear plugs and an eye mask! They are both cheap (or free!) and have saved me more times than I can remember. I still use an eye mask that was provided to me years ago on a long flight. As for ear plugs, I find the ones that are made for women with snoring husbands the most comfortable. (I realize this is ironic on multiple levels.)
Pro Tip: If you use the trifecta of an air mattress, eye mask and ear plugs, you can sleep comfortably in airports, in hostel dorms, under the stars, on your friend's floor, or almost almost anywhere else.
Fatigue is one of the greatest sources of discomfort on the road. And one of the biggest causes of fatigue is traveling too quickly. You'll have some of your favorite life experiences when you travel. Just make sure to slow down enough to thoroughly enjoy yourself.
Keep in mind that travel itself is not always comfortable. Hostels can be noisy (see above). Bus rides can be cramped and bumpy. You might get sick from the water. You could even be delayed due to a natural disaster or political unrest. Often you can avoid these situations, but not always.
My advice is to accept the hand that is dealt to you. If you really wanted to live the most comfortable life possible, you would never travel in the first place. Giving up control is a big part of being on the road. At some point, you'll have to accept this and move on. If nothing else, you'll end up with a good story.