It's a well paid, very satisfying, professional job which entails several years of complex training and a lot of hard work before one qualifies as a controller. Controllers are required to pass a stringent medical examination similar to that of a pilot and to undergo regular medical exams thoughout their careers. But I thought you were more interested in flying???
I think you probably need to investigate elsewhere to get a basic idea of what is involved. Take a look here for starters:
NATS careers