I'm studying civil engineering, I knew in advance that it would be hard, (& it is =)) but it's sooo interesting

& the jobs in the future are also verry interesting
I don't think you have to chose your study on the things you've studied before, I know a friend who started economics at the university because that was "the only thing he knew something of" ... he failed, because he only chose it because he thought he had an excellent background for it.