That's why it's called "work".
Or even better labour from Latin labor , laboris which also means harm , misfortune or agony .
Interesting, in lunfardo a dialect of the Argentinian and Uruguayan spanish with heavy influence of italian, laburar means to work... estoy laburando means i'm working.
Being the lunfardo origin, in the tango culture, with its sometimes gloomy view of life, it makes sense that it associates the work with agony and harm.