When I was working at a Bike Shop, I was standing on one side of the display, talking about what I was going to do and how I was going to do it. It was a very in depth external monologue (I have both like yourself). As I was coming around the other side of the display, the owner happened to be standing there and said, "Wow, that was some kind of a conversation you just had with yourself. I hoped you were able to solve whatever problem you were discussing." He had a big grin and we both laughed about it.
He told me later he too does a lot of internal monologue for stuff as well and was told by some super successful businessman that this is a good thing and a hallmark of successful people so don't be discouraged by it.
Girlfriend, coming in from outside: "Who are you talking to?"
Me: "I talk to myself. You know that."
Gf: "Oh right. You also whisper to yourself, which is scary."
Me: "Scary?"
Gf: "It sounds demonic."
Which, to be fair... Evidently, my internal monologuing gets quite a bit vocal even with other people around.