The fourth and final agreement—Always Do Your Best—allows the other three agreements to become habits that will change one’s life. Ruiz begins the chapter by explaining that one’s best always differs depending on life circumstances, energy levels, emotional states, sobriety, etc. Nevertheless, Ruiz advises people to keep doing their best—no more, no less. Those who try too hard expend more energy than necessary, and it still won’t be enough. On the other hand, those who do less than their best often feel frustrated, angry, and guilty.

To illustrate this point, Ruiz cites an example of a man studying at a Buddhist temple. The man wants to transcend suffering in this life quickly, so he asks his Buddhist master how long he ought to meditate. The master responds that if he meditates for six hours, he may transcend in 10 years. The man asks how soon he’ll transcend if he meditates for eight hours instead, and the master replies that it would take 20 years to transcend. The man is understandably confused. The master tells him that if he can do his best in two hours of meditation but spends eight, he’ll miss the point of the meditation and only grow frustrated and tired.