Ajahn Chah instruction on breathing meditation:
"Look on the breath as if it were some relatives come to visit you. When the relatives leave, you follow them out to see them off. You watch until they’ve walked up the drive and out of sight, and then you go back indoors.
We watch the breath in the same way. If the breath is coarse we know that it’s coarse, if it’s subtle we know that it’s subtle. As it becomes increasingly fine we keep following it, at the same time awakening the mind. Eventually the breath disappears altogether and all that remains is that feeling of alertness. This is called meeting the Buddha."
~ Ajahn Chah