Usually my husband and I study twice a week with Sara Rose Page who runs Yoga Sanctuary.
We almost always used to start with a big deep breath in the lungs for me to move it form the singer's belly all the way up to the lungs(Yoga Sanctuary teachers in Thorne's Marketplace on Main St. Northampton MA are great singers as well and Rose plays the singing bowl masterfully). Once I was alone with Sara and we did this and she said, "Yes, Prana, the breath, the full breath." (I am compressing this and meant to write this months ago). "But you know also the Sanksrit word, 'porna'? It means the fullness of a thing unto itself." Not the philosophically workmanlike, "sufficient unto itself" or something ontological(or is it?), but just fullness and enough-ness.
I leave it to others who ask why many people don't feel like they're "enough" or porna in the first place!