Sarah Bakewell writes in How to Live: Or A Life of Montaigne in One Question and Twenty Attempts at an Answer:

Mindful attention is the trick that underlies many of the other tricks. It is a call to attend to the inner world—and thus also to the outer world, for uncontrolled emotion blurs reality as tears blur a view. Anyone who clears their vision and lives in full awareness of the world as it is, Seneca says, can never be bored with life.