When I think of comfort, several things come to mind. A chair
Obviously, because it is comfortable. In a chair I can give my back a break, cross my right leg over my left knee and stretch my lower back muscles, and I can lean my head back and close my eyes if I'm tired.
Anything. A magazine, book, or old journal entires. I usually have my iPad with me, so I'll typically be reading a book from either the iBookstore or the Kindle Store, or one of the several magazines I read on my iPad (The New Yorker, TRVL, and Flight Training Magazine).
Hot or cold. Usually a tall black Italian Roast in a white ceramic mug with the Starbucks logo on the side. Starbucks is my third place, and I feel very comfortable when I am there drinking coffee.
Combine all three and this is when I'm most comfortable:
I can be anywhere in the world and as long as I have these three things, which is not hard to do, I can be very comfortable.
How about you?