Nature, the cause of depression

Countryside depresses me. I am ok for a day trip, and I can stand nature for several days in summer if I have good company, good facilities, and am more or less on the move, but staying for longer than that in a place where there are only forests or fields around makes me think of slashing my wrists and putting myself out of my misery. (I obviously don't actually do it, but get the hell out of there instead.)

Where does that come from? (I don't mean the dislike of countryside as such but such a strong reaction.) I am not generally depressed or particularly prone to depression. Do other people get this? Do some people get the same kind of thing in the cities?

I sometimes wonder how long it would take me to actually do it (if ever). No, not going to try to find out.