The novice comes in to the monastery and says "I really want to be a monk. What is it you do at one of your sesshins?"
The monk thinks about it and says "I sit on a cushion and I stare at a wall. Oh, and I breathe."
The novice says "Okay, I'll do that. How do I do that, exactly?"
The monk gets him a cushion to sit on, and tells him "Now breathe."
The kettle whistles and the monk leaves the room to take it off the heat.
The monk comes back in a minute later, and looks at the novice.
The novice looks frantic. The monk sighs.
"Breathe out. Once you've finished breathing out, breathe in again. Keep doing that."