I had lucid dreams as a teenager too, and completely forgot about it. Then about a year ago it happened again - and I remembered how cool it was.

I find I can nearly always do it if I wake up in the middle of the night then just think about it as I fall back asleep. I guess my subconscious then keeps a look out for weird stuff... "That elephant wasn't there when I looked a minute ago. Wait, elephant?! I'm dreaming!" Then it's flying time.