This has got to stop; problem is, no one can stop it but me.

I know that subject line sounds like something a comic book superhero would say, or, at least, think. However, I'm not talking about any outside force. I am having a problem, but that problem is not with anyone else, friend, enemy, or otherwise. It's with myself. The literature says that it is a symptom of Asperger's Syndrome, yet, I think I can overcome it, or, at least, limit it to the point where it won't bother others, which it has done almost my whole life. What is that problem? Talking out loud to myself.
Before you say something like, "I'm not autistic, and I do that, too!" let me explain what I mean. You might say a few words to yourself from time to time, but this is beyond that. This is to the point where, if you were in the other room and heard me, you'd think I was either on the phone or had someone else in the room with me. It gets to where most thoughts I have come out of my mouth somehow, whether by talking loudly, whispering, or some other way.
Now, I will explain the history of how this started. When I was a little kid, I watched quite a bit of television. I didn't understand about how TV cameras and all that stuff worked; I thought that everything I saw on TV was taken directly from someone's eyes. So, naturally, I thought everything I saw was on some channel, somewhere, which led me to talk out loud to an audience that wasn't there.
Eventually, I realized that there were TV cameras and all that. However, when I got to be middle school age, I was left alone a lot. I'm not blaming anyone; no parent should have to hire a sitter for his/her 11+-year-old son who is capable of taking care of himself and the house just fine, autism or not. Still, when I got left alone, since I had no one to talk to and nothing to do, I would start having long conversations with myself. I did it when my mom went to the store; I did it when she would sleep after working a 12-hour night shift; then, later on, I would do it at public places like my church, MovieStop and even at my first job, which I very well may have lost because of that bad habit. It's no one's fault but my own. While doing it at home is okay, because it's usually not really bothering anyone, when you're out in public, people get scared/repulsed/etc. because of that sort of thing.
Now, here's the thing: I still do get left alone a lot, plus I volunteer at my local library, which is very much a public place, and, I'm planning on getting a job as soon as possible, and I don't want to annoy/put off/etc. any of my co-workers by doing what I've talked about in this post. So, there's never been a better time to cure this habit. The question is: How? I've been talking to myself every day for as far back as I can remember! So, this is going to be a doozy of a habit to break. I'm sure I can curb it; all it takes it a lot of willpower. I may not be able to completely stop doing it, but I think I can reduce it enough to where it won't bother anyone.
Here is my question to you: Do you have any suggestions for how to stop doing this? Let me know.