There are two aspects of mindfulness: first, to remember what causes suffering and needs to be avoided, and what brings happiness and needs to be accomplished; and second, to be constantly vigilant lest we fall under the power of delusion.
If we mechanically follow our wandering thoughts instead of remembering to investigate our mind, afflictive emotions such as craving, and hatred will rise up strongly. Whenever these assail your mind, you should react just as if you had seen an enemy coming at you: lift the weapon of mindfulness and resume your investigation of the mind.
Simply by turning on the light, you can instantly destroy the darkness
– Dilgo Khyentse Rinpoche