Acharya Prashant explains that the mind's tendency to dwell on the past or ideologies is a result of lacking a central focus in the present. He clarifies that being in the present does not mean merely concentrating on current activities, but rather being centered in the truth. The past and future act as fillers that occupy the mind when it is not centered on what is essential. Just as a bowl fills with air when it is empty of water, the mind will fill with 'rubbish' or nonsense if it is not given the right thing to focus on. He emphasizes that the mind is a vacancy that requires occupation; if one is centered in the one thing that matters, distractions and past thoughts will naturally stay away. Instead of trying to fight or analyze the nonsense, one should focus on the right center to avoid frustration.