The first couple of times I've spun in lucid's it's been like I closed my eyes in the dream and immediately the world faded away and I began to lose consciousness/awareness.
If you don't remain calm, you will wake up. A fight or flight fear/alarm response will increase your heart rate and cause an adrenal response. You'll wake up. Be peaceful, calm, but engage your conscious mind thoroughly. Remember it is a dream, always. Try interacting with your dream landscape to stabilize the dream. Rubbing hands I've heard helps. I've tried touching everything and talking to DCs.
Usually my DCs are the ones that tell me I'm in a dream. But consciousness never seems to last for long. When I've made it a point to experience sensations in a dream to keep lucid, my conscious mind fades into sleep and my new dream goal has become to touch things randomly and I've already forgotten it was a dream...