Vijnana Bhairava Tantra · Dharana 28 · Verse 51
Gap between breaths all day
While walking, talking, working, or eating, keep a quiet thread of attention on the pause between breaths. You are not trying to look spiritual in public. You are simply declining to give the mind a continuous moving object.
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However you are and wherever you are, cast the mind again and again to the point where the breath ends. As its restless movements fade, within days something altogether different appears.