Sw Niranjanananda says that a perfect breath control can be seen when u breathe in and out just once in one minute. It may explain why Prahlada used to say innnnnnnnnnnnhaaaaaaaaaaaale and exxxxxxxxxxxhale for so long.. we idiots in the advanced teachers training class used to feel stressed just trying the length of that amazingly drawn out inhale and exhale. Oh, to be able to do that would be soooo meditative. I am trying nowadays to at least watch my breath. But let us at least try to slow the breath down now, what???