Below is one of my favorite extract's, as I remember being asked the same question many, many time's when I was about to Leave school and I still don't know to day what I want to do.
Altought I think it has become more important in this day and age, to at least have a direction with so many university degrees being so specific in their scope and range.
You could end up having to go back and start over, if your degree is not in the same filed as what you end up deciding, what you want to do is. After all there is no point spending 4 years doing a degree in computers. To then decide you want to be a vet.
I'll start by telling you something you don't have to know in high school: what you want to do with your life. People are always asking you this, so you think you're supposed to have an answer. But adults ask this mainly as a conversation starter. They want to know what sort of person you are, and this question is just to get you talking. They ask it the way you might poke a hermit crab in a tide pool, to see what it does.