Acharya Prashant addresses the nature of fear by observing a student's hesitation to ask a question. He points out that fear does not exist within the actual performance of an act, but rather in the preceding thought process. While the student was afraid for an hour while thinking about asking his question, he was not afraid while he was actually speaking. This demonstrates that fear is a product of thinking about the future and anticipating consequences rather than the reality of the present moment.