How can people go thru doing boring monotone work 40 hours a week all their life?

A lot, if not most of people work monotone and boring jobs, whether they work at an office or some alley little store. There are some jobs that give you some diversity in your work. Like driving around doing service in different places, if you are a technician or a plumber for example. Being a police officer, firefighter or perhaps some parks service job. But other than that how can people bear doing same thing every day in exactly the same place with exactly the same people and 4 walls?