I don't do this often but occassionally after a run I'll sit down and meditate and wait for my monkey mind to start thinking. I achieve this momentary clarity where I have no inner dialogue, I hear my heart beating and feel my chest rising and falling as I breath but I don't notice any thoughts.

I get this sort of serenity from exercise. Exercise is one of the most powerful tools to improve cognition. For me I find most cardio monotonous, I prefer to lift or do Bjj for fitness which requires mental and physical sharpness to be good at