When I was younger, I had one major life goal. I actually met that goal, then found out it wasn't as awesome as I'd expected and have now started over at square one.
In general, though, I think we are the ones who stand in the way of our own dreams. It is so easy to become bogged down in what we're already doing, even if it isn't satisfying. New is scary and at least the known is a known. I'm really trying to push my boundaries more, though. I think the risk is worth it, I just have to remember to convince myself of it, day by day!