Acharya Prashant addresses the issue of overthinking and anxiety by emphasizing the need for a sense of purpose and importance in life. He explains that the mind cannot tolerate a vacuum and will inevitably fill itself with trivial, random thoughts if it is not occupied by something truly worthy. He compares these random thoughts to pathogens that are always present in the environment; one cannot eliminate them but can develop 'inner immunity' by prioritizing what is truly important. When a person lacks a sense of the worthy, their mind becomes scattered and they waste their life doing 'nothing in particular.'