I listened to it while lifting, and now every time I lift while listening to something else I'm like "ugh this book is fine but it's no Silmarillion"
I've listened to dozens of great books at the gym, but there's only two I've wanted to listen to a second time: Silmarillion and Norse Mythology by Neil Gaimon
There's just such a vibe to those books. The stories are short, but they feel ancient. I feel rooted when I listen to them.
That and when I'm trying to fall asleep and it's winter. I'm cozy and feeling the hygge. I've got my warm drink and blankets and I want a bedtime story of how Morgoth was cast down
If you're into mythology, generally, I recommend "Mythology" by Edith Hamilton. The audiobook is great, too. I read and reread that so many times between middle school and my classics courses in college.
Eventually picked up the audiobook read by Suzanne Toren. I'm pretty sure it's the most recent one available through audible and I liked her narration.