Meditations by Marcus Aurelius.

Rather than being just a book, it is a life coaching guide that helps you to γνῶθι σ(ε)αυτόν (“know thyself”).

Have you tried with audio books?

Its really hard to pick a title (especially just one), so I would go with the The Little Prince by Antoine de Saint-Exupéry (still re-reading it thru the years), Emil of Lönneberga and The Brothers Lionheart both by Astrid Lindgren.

Why?

Well, a good book makes you live thru the story told and gives you pleasant experience.