Burns, I became lucid in the past mostly through nightmares.
Once, I was in a graveyard and a ghost kept coming at me, slowly but surely, and I was backed up against a tombstone. In that moment, I knew that I was dreaming, but instead of taking control of the dream, I told myself that if I could move my arm I would wake up and be safe. I kept saying "move your arm! move your arm!" until I did, and I awoke.