By practice alone, one realizes the extraordinary value of Left Right Breath. Don't "control" the breath. Let it go. Practice everyday, many times a day, for a really long time. Then you will know. Support your elbows. Hands in prayer pose. Relax your neck and shoulders. You can do this!
After many months, your breath will become very refined, slow, and filled with deep contentment. These courses will take you there.