Pablo.. It's like any other professional job - if you are properly trained and capable then you'll be able to do it. It's no harder than flying a jet, operating as a surgeon, etc. I did it all my life without any problems yet the thought of teaching a class full of kids turns me into a trembling wreck.
Training is thorough and you won't be let loose until everyone is totally satisfied that you are safe.
Take in what Gonzo has said - he knows what he is about.
Lastly, what you hear on the airband is only a fraction of the workload. The controller will be liaising with other controllers on the telephone and by direct converstaion with those around him.