Read for about 15 minutes in the morning.
In his 2019 day-in-the-life episode, Greenfield names this as the book he was reading as part of his morning routine.
“Book: Stillness is the Key by Ryan Holiday”Ben Greenfield
Source: A Day In The Life Of Ben Greenfield: Ben's Exact Morning, Afternoon & Evening Routines (podcast, 19 Oct 2019)