How do you pick up and travel the world?

I see people do it, and I don’t understand the logistics.

I think, if I wanted to do that, I’d have to quit my job halting any progress I’ve made in my career, then go off on this adventure. Then a few weeks or months in, I’m out of money and in a country I don’t speak the language of, so I probably can’t get a job there, and then what? I’d have to come home, live with a friend till I find a new job and start over? Save up money for a while, then quit again and go blow it all on an elaborate “vacation” of sorts instead of investing, saving for my future, or to start a business of my own I desperately want…

I just don’t understand how people do it. The answer I usually receive is, “I think you just do it.” =/