It is important not to mistake the menu for the food. An exercise or action designed to cultivate a neigong is not the neigong.

It is only when no doing occurs and the effect is present that the neigong can be said to exist.
A person with a neigong has the effect all the time.
It does not come and go. It is part of their everyday movement.

This is why it is considered to be internal power. Neigong is inherent. It remains. It is a part of you.