People have went through years or practice to archieve lucid dreaming. It can just happen coincidentally too.

I remembered i had a lucid dream like 6 years ago. I was in the kitchen and my maid was serving fried rice...and then it suddenly popped into my mind...hey...i am dreaming...3 secs later, i woke up.

Another time, i was having this nightmare. A witch was chasing me. And i was like so frightened. And suddenly it popped into my mind, that I AM DREAMING! I had to wake up! So i cupped my hands over my eyes and shut them tight. When i opened my hands...hey...i'm in bed again! But...i dozed back to sleep. And sure enough, there was the stoopid witch again. realised i was dreaming and woke back up...and this repeated for quite some time. At that time I didnt know the advantages of lucid dreaming, if i knew, i would make full use of it and continue dreaming. Geesh, what a waste.

From then on, i never had lucid dreaming ever again. Alot people spent YEARS practicing and it never happened. I myself fear this. What if all these years of practicing is just a waste of time? *sniff* *sniff* some ppl are juz so lucky!