In the beginning you should stick to the smaller numbers and increase when you feel comfortable with it.
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WARNING!!
DO NOT overdue any breathing exercises!! More here is NOT better! The holding recommendations are only examples. Holding for a count of less is fine. Do whatever is comfortable. One should never feel short of breath, or experience any stress, or the need to gasp for breath when performing any breathing exercises. BREATHING EXERCISES ARE NOT LIKE CALISTHENICS! PUSHING OR EXERTING YOURSELF CAN RESULT IN CENTRAL NERVOUS SYSTEM, I.E. BRAIN DAMAGE. ....."