It presumably will, however be somewhat easier than being on the space station, which people have managed for over a year with relatively few adverse effects.
Of course, these are the best of the best, specifically selected because they are focused and driven, but we aren't going to be sending just anyone to mars either.
Its difficult to fathom quite how much there is to do in space. Astronauts aren't sitting around, but constantly performing maintenance and fielding science requests from all the world's top researchers.
Consider additionally people living about a nuclear submarine have similar freedoms, and there are many that willingly get back on board even when their mandated time is up because its not a terrible job. Some things the human psyche can work around when you have a constant supply of mental stimulation and a fulfilling life.
I'm guessing that being on Mars isn't even remotely similar to being out in the harshest Earth environment.