Awareness! If you keep doing reality checks in real life without actually stopping and asking yourself if you're dreaming, you'll end up doing the same thing in the dream itself... Without becoming lucid. So be sure to really be skeptical about the matter - both dreams and waking life feel real because even though we "know" we're awake, in dreams it's the same thing until you do an RC.

It's good you're remembering dreams every night, so keep it up.