knowing what you want

I have great admiration for individuals who know what they want in life, who set goals, and who plan to achieve them. I wonder how they can be so sure of themselves -- how, exactly, do they know that they know? The impending end of this recognizable unit of time in my life (schooling) requires some decision-making. Specifically, I need to figure out what I really want to do.

The only trouble is, I think that I have spent too much of my life concerned about what it is that others want me to do. You would think that I'd be able to tell the difference by now, having reached adulthood. I should know what my preferences are, and the types of work that make me tick. Unfortunately (?), I think that my habitually denying between what I want and what others want of me has caused the difference to become blurred.

I keep saying that I wish I had a robot (computer program?) to which I could give all sorts of information about myself -- my likes and dislikes, my habits, my preferred lifestyle, and things that I think I enjoy. It would take all of the appropriate data and variables and tell me what I should do. Or what is the next best thing?