I believe the answer to that is that lucid dreamers have a token symbol they regularly keep in real life that cannot attain a specific state in reality; if they

I believe the answer to that is that lucid dreamers have a token symbol they regularly keep in real life that cannot attain a specific state in reality; if they keep this token so persistent in their life that it inevitably ends up in the dream, they can interact with the token to determine the dreamstate by making the token do something impossible. This boolean answer hopefully trickles up to you just enough to go "whoa!" without waking you - at which point you're free to dream about the 3 things people do with lucid dreaming.