We're just going to come out and say it: it's difficult to become an air traffic controller. All applicants must be under thirty-one years old, pass a physical examination, and be a United States citizen. Then you'll also need to find, apply, and actually be selected for the job. And selections can be pretty much random for qualified applicants.
Then you must pass a pre-employment test that takes roughly eight hours to complete. (Don't worry—they'll let you pee at some point.) Upon completion, applicants train at the FAA academy in Oklahoma City for twelve weeks. After the completion of the program, candidates are assigned an air traffic control facility where they will train for two to four years to become certified.
There's a whole lotta steps, but the rewards are pretty worth it.