One chapter a night is a workout for the part of you nobody can see at the gym.

Attention is trainable in the same unglamorous way strength is. A chapter a night is not impressive on any single night, and that is the point, because the gain comes from the repetition rather than the size of the session. Nobody will compliment the result, since the part being built does not show up anywhere visible. It shows later, in how long you can stay with something difficult.

Put the book where your phone usually lands at night. One chapter, even a short one, then stop without demanding more. Count nights rather than pages.