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'Cause most of us are heaving through corrupted lungs
'cause most of us are heaving through corrupted lungs' could refer to lungs destroyed by smoking.Meaning those who have not smoked before are lucky because most teens are breathing through cancerous lungs. 'Destroy the middle it's a waste of time refers to teenage years where adolescents are most prone to doing drugs, and smoking...which is explained at the beginning of the song.