As a seventy-nine year old 'retiree' who has been out of paid employment for twenty years I can say that 'dream careers' change as we change. That is, the dream career of the teenager is not the same at forty, or even sixty. When we're young we desire to 'expand into life.' We want adventure. In my case I did this by joining the Navy. When we're older we desire to assimilate and teach what we've learned.
At twenty-four, when I got out of the Navy I still wanted more adventure so I got it by joining an government department where I could travel and do interesting work - Civil Aviation. My 'adventure period' lasted from roughly 18 to 41, and then I started looking for a different type of career, one where I could use my previous experiences e.g. writing and teaching.
But that was not to be. I found myself largely in work I disliked. Yet in my mind my 'dream career' (until I retired) was to be a professional public speaker travelling the world and presenting at audiences away from home. - until I actually started to do so. I realized the speaking represented only about 10% or even less of the job. Most of the rest involved marketing and promotion and...lot's of waiting around airports and the like.
It was then I realized the loneliness of living in a hotel or motel room, of dining alone and lots and lots of travel, once more alone. Not that I mind solitude. I enjoy it. But it is nice to be among old friends every now and then.
And so the point I make is that a 'dream career' will not necessarily make for happiness. To get that you need to work on the 'inside.' That is, on what is inside you rathe than what is out there.