I think the absolute hardest thing not only about circus, but following your dreams in general, is "the space between." Those hollow times in your life when you just finished one stage and are (perhaps not-so-patiently) awaiting the next. It's in these times when fear rears it's ugly head and says, "See? I knew you'd never make it. Yeah, you had a glimpse of what could be, but now it's over. Time to give up and face reality." It's also in these times that the negative comments you are usually so quick to brush off actually start to gain access to your heart, feasting on your positive spirit and darkening your hope.
The most important part of human interaction in general is communication. Speech, gestures, body language. How we interact with one another makes a huge difference as to how we get along and how things get done. For a Towner (someone who works a town job, or a non-travelling job), if you don't get along with a co-worker, you can go home at night and forget about them for a little while. You get long weekends and vacations away from them to reset. In circus, you are with the same group of people day in and day out. You work together, eat together, relax together, breathe together, sleep in trailers so close you can practically dream together. At times, this can be incredibly frustrating, but also has the potential to be amazingly rewarding.
Over the years, I've had the great pleasure of working with people from all over the world. In Australia, I worked and studied with folks from Australia, New Zealand, Japan, Malaysia, Singapore, Indonesia, the Philippines, China, Ethiopia, France, and other Americans. Here in the States, I've gotten to work and perform with others from Russia, Romania, Canada, England, Ireland, Brazil, Mexico, Argentina, Columbia, Peru, Chile, Guatemala, Honduras, and many other Latin-American nations I'm sure I am forgetting! (I have also gotten to perform, myself, in El Salvador.) It is absolutely amazing to chat to these beautiful people, learn about their cultures, and share life together.
But therein also lies an inherent problem: language. How do you truly get to know someone if you don't speak each others languages?