I found lucid dreaming by accident; it just happened to me a few times before I discovered some people called it "lucid dreaming".

There are some interesting mental experiments you can do when lucid dreaming, like the ones where you look at yourself in the mirror. What do you see? What do you see in the mirror when you move? What happens if you move into the mirror? The answers to these questions tend to be very interesting, but also very diverse between people.

What were your answers?

It's rather creepy. The vision of yourself in the mirror tends to be distorted, and if not (in my case was not), it gets distorted with movement. As if the brain couldn't process it well, or something like that. And usually, in dreams, going into surfaces makes all your surroundings change (at least that was what happened to me, it was like teleporting).

Google for Lucid Dreaming and Mirrors, it'll get you to very interesting results.