This state is sometimes called the fictional daydream or, in German, Kopfkino, literally “cinema in the head”.
The challenge for the writer is writing five words that will ‘hook’ or immerse the reader in the story. Then keeping the reader immersed. Entire books have been written on how to do this and “Deep Point of View” so I won’t try to cover all of that here. Your editor will work with you to assist you in this.
How do you find solitude in the middle of a crowd? On a train, on a bus, at an event that has lost your interest? Take out your favourite book!
I recently listened to “Romeo and Juliet: A Novel” by David Hewson, narrated or performed by Richard Armitage. In an interview about the book, they spoke about the German expression Kopfkino, literally “cinema in the head.” What a fitting way of expressing what happens when one reads, or listens to a reading or performance of a book.
Nobody but you knows what goes on in your head. Even if you wanted to, even though you can try to express it, it’s rare that you could actually do so. There, in your head, you are alone with your thoughts and the images you see.
Almost as good as writing, seeing a new story for the first time, immersing oneself into a new world, literally making it up as you go. Populating your new world with your own characters.