first lucid dream, kinda and a question for you guys :)

Date: 8/27/2016

So ive had ome before where i was hanging onto a train and when i realised i was dreaming i then woke up This time, i was in my downstairs toilet and i looked in the mirror and performed a reality check. I was able to realise that i was lucid and i walked towards my door. I got really excited and tried to calm down. When i did so, i couldnt move in my dream and i fell back asleep Does anyone know why i couldnt move? How can i make my dreams when im lucid last longer? Thanks :)