The rocking horse moves with energy but goes nowhere, so dream books read it as effort that stays in place, or as nostalgia for the safe adventures of childhood.
When this appeared in your dream, what were you feeling?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.