How a Self-Published Book Became a Best Seller

Last summer, a book changed Kohn Glay’s life.

A TikTok ad had steered him to “The Shadow Work Journal,” a slim workbook that directs readers to explore hidden parts of their unconscious — their shadow selves, in the book’s vernacular. He ordered a copy, and soon was back on TikTok, fervently recommending it to his followers.