My career was kind of decided when I discovered I was reasonably good with certain skills, such as problem solving, methodical thinking and having an 'ability' to understand and get my head around things. For information, I am a technical consultant. I have worked for a number of companies and run my own consultancy, but now work for a global service supplier.
I identified something I had a skill with, and ran with it. However, when I was growing up I often thought about being a doctor (having spent lots of time in hospitals), but the downfall was I found academia frustrating, prefering to see things happen in the real world than read about them in a book. So the IT route seemed a little more suitable to this, particularly as there is no strict requirement for a particular qualification (as you can guess, IT related degrees and diplomas are half out of date by the time they reach you in the post, so really the conceptual side of things is pretty much what you get from University / School)/
However, as I am now a little older, I regret my decision. So how did I choose my career - I identified something I was good at and thought I could really excel at, and developed it. It worked for me so far, I have a good job, earn a good wage, drive a reasonable car, can buy myself pretty much what I want.
The best advice I can give (and this is a concept I think my in laws have yet to grasp), never let anyone put you down. Nobody is different from you, and at a basic level you have the same opportunities as everyone else. Pick something you think you would like to do and go for it. If it doesn't work out, look at where you went wrong and try again with the benefit of experience. Also, risks are OK - some of our caveman ancestors (or me today as I haven't shaved) took risks, went our, caught buffallo, scored a hot cave girl (preferably with a striking resemblence to Amber Heard) and feasted. The cautious ones, well, they sat in thier caves and starved.