Early books: Arrow to the Sun and Grimm’s Fairy Tales and Hans Christian Andersen and The Hobbit - all very stimulating to imagination.
"Yoga Vasistha" has nothing to do with the physical aspects of Yoga i.e. Asanas (though some passages do talk about them) but deals purely with the internal/intellectual aspects of the mind. It is a very long book with lots of Allegories/Similes/Stories/Repetition and so you have to read it slowly and with patience.
I recommend reading "The Concise Yoga Vasistha" (an abridged version) before reading the unabridged "Vasistha's Yoga" both translated by Swami Venkatesananda.