Many movies that are created nowadays trigger fear. Such as the movie, The Exorcist, which is about a girl that is possessed by a demon or Satan himself. This fits the theme because horror movies can keep you up at night by FEAR.
Reading scary novels can make the emotion of fear trigger in. Books by authors like Stephen King can trigger fear through a human body like wildfire. This fits the theme by making peoples skin crawl.
There are many different fears. Some fears are phobias which are abnormal fears, like ophidiophobia, the fear of snakes. This fits the theme because your phobias can give you nightmares at night because you FEAR that your phobia can harm you.
Definition of fear - an unpleasant emotion caused by the threat of danger, pain, or harm
In “FEAR.”, Kendrick explores 3 instances of true terror at ages 7, 17 and 27 respectively. His lyrics are deep and can sometimes touch your soul in a somewhat FEARFUL way.
The song, "FEAR." describes how he had feared a lot all throughout his life about many things. This fits the theme because he talks about how he has been scared at different ages of his life.