Because i think that no one has actual experience in this category, i decided to research the answer. And here is what I found: Air traffic controllers are people who operate the air traffic control system in order to expedite and maintain a safe and orderly flow of air traffic and to help prevent mid-air collisions. They apply separation rules to keep each aircraft seperated from others in their area of responsibility, and they move all aircraft safely and efficiently through their assigned sector of airspace. It is because these professionals have a demonstrably large responsibility while on duty, the ATC profession is often regarded as one of the most difficult jobs there is, and it can be notoriously stressful during busy periods. Air traffic controllers are usually people with excellent memory, are organized, and have spatial awareness – that is to say they must have the ability to think in four dimensions. They are quick with numeric computational skills, are assertive but calm under pressure, and are able to follow and apply strict rules and yet be flexible when necessary. Air traffic controllers usually start their career in their twenties and retire from actively controlling in their fifties. They must undertake a strict aircrew medical annually, be able to communicate and lead a sober life. You will come into contact with these professionals whenever as a pilot you enter of need to enter controlled airspace. Source: http://www.etraffic.co.za/affiliates-flying-01-Air-Traffic-Controller.html For extra reading: http://www.bls.gov/oco/ocos108.htm

Air Traffic Control is stressful because every day a controller is responsible for hundreds and thousands of lives. One wrong clearance can lead to devastating results.