How can I become more interested in learning?

I want to be someone who comes out with the most random knowledge on so many different topics. I love people like that. Most of my friends are really knowledgeable and it leaves me feeling like I want to know so much more and, more importantly, be able to TALK about the knowledge that I possess. I'm mostly someone interested in deep conversation, learning about who people are, talking about life, and psychology -- when it comes to those I can never shut up. But I want to be more interested in reading, I want to find myself having lots of opinions on politics, science, religion, history, etc. How can I possibly have opinions on those things when I don't care enough to read up on them? I don't know enough and it bothers me. It bothers me more than most things, actually. I like to think I am reasonably well educated but then I don't retain much of information I get from reading to talk about it at length. I know I'm only 18 and I have plenty of time to grow and learn but I feel like I don't have the mind for it. Not in the sense that I'm incapable of learning and expanding my intellect. Just that I don't know where to begin and I don't know how to develop a deep interest in reading up on things. I don't even know if I can be that person who can talk at length about everything I have learned. My verbal skills aren't so impressive. I have trouble forming long, articulate sentences. I think a lot of that is down to my extremely poor memory though. I forget what I'm saying a lot of the time and sentences end with "Uh... what was I saying? My mind wandered." Or "Nevermind". I know reading a lot more will help me but how can I actually start becoming the person that I want to be? How can I have my own opinions and become more interested?