"Navi" means "navel" as in the belly button, and "kriya" comes from from the Sanskrit "action, deed, effort."
Navi Kriya is the process of making the abdominal lift dynamic between the navel and the area of the inner spine that is right behind the solar plexus (all the way back behind the hollow at the bottom/center of the ribs). The diaphragm is in this area too, so Navi Kriya can also be viewed as pulling the navel repeatedly up toward the back of the diaphragm in a gentle rhythmic cycle.
Navi Kriya is very powerful and can be dangerous.If you have blood pressure, heart or abdominal health issues, or any other doubts about your fitness for navi kriya, please consult a doctor.
Become well established in basic practices as outlined in "Main Lessons" above before attempting Navi Kriya. If any ecstatic conductivity has begun, Navi Kriya can cause premature kundalini awakening which can result in internal burning and emotional problems.