This is a very weak teaching. The mind is the mind and will do what it does. Our responsibility is to transcend the mind throught realization that we are not our minds. Tinkering around with positive and negative thoughts keeps us spiraling in an endless loop. The only way out is to stop messing with the mind and turn attention to that which is beyond mind, beyond positive and negative, to that which is already peace, that which is already still. That teaches us.