Acharya Prashant explains the fundamental difference between personal interest and a true calling. He states that interests are products of one's conditioning, upbringing, and social environment. They are rooted in a false identity and pull the mind away from its true center or the self. Interests are predictable and reinforce existing patterns and identities, such as those based on gender, religion, or profession. He emphasizes that interests are essentially the mind running away from its reality, driven by past impressions and external influences like advertisements or family expectations.