@"Beryl C." I know what you mean. That sounds like a good book. For me it's reading or doing a jigsaw puzzle or watching cute YouTube videos. In today's psych speak it's called a flow state. "the mental state of operation in which a person performing an activity is fully immersed in a feeling of energized focus, full involvement, and enjoyment in the process of the activity. In essence, flow is characterized by complete absorption in what one does, and a resulting loss in one's sense of space and time" - Wikipedia.
I've been working with the same registered psychologist for a few years now and she has helped me enormously. I've finally got some practical tools that help me.