There's no real good way to convey to someone who has not yet experienced lucid dreaming exactly what it feels like to pop into lucidity. However, I'll relate a little story that I think may give a bit of idea of that moment of realization:

Imagine there is someone interested in the topic of lucid dreaming. We will call this person "the Wonderer." The Wonderer has heard a bit about lucid dreaming, and would really like to know if they can do it too. The internet is a great place for quick information, and after looking around a bit, the Wonderer comes up with some links, one of which just happens to be Dreamviews.

It's a great discovery... there are apparently a lot of people talking about Lucid dreaming there. There's a forum where people can share techniques and experiences. Maybe the Wonderer can learn how to join in on the fun after all!

After awhile of poking around on the forums, the Wonderer sees a thread in the Newbie Zone that looks interesting. The thread has a title that the Wonderer just can't resist clicking on. It is called "Here's what it feels like:"

"Maybe I can get some answers in here!" thinks our hero, and watches the page assemble in the browser window.

The Wonderer begins to read the text which offers a short story about a person who is interested in lucid dreaming. The person described in this story visits Dreamviews for some information about the topic. As the Wonderer reads further down the page, they begin to sense some familiarity with the story... it seems to be describing someone going through the exact same motions, having the same thoughts, reading the same text... until finally the realization hits from some far-off corner of the brain. The story is about the Wonderer! The reader of the story is the Wonderer.

And just as soon as the Wonderer realizes this, they become aware of their power. They can stop reading, reply to the thread, go to another thread, turn off the computer, etc. In other words, the Wonderer has complete control over how this story ends!

While you were reading this, you were recreating the story in your head. But awareness of the true nature of the story probably did not hit you right away. It isn't often that we read a story that unexpectedly turns out to be about ourselves.

At that moment when you said to yourself "oh brother... it's about me..." the little flip of recognition you felt is very similar to the flip of recognition in a dream: "Oh... it's just a story that happens to be about me."

So there it is, as best I can describe it. Now go create the ending!