Explanation:

The expenditure of inert energy in the world, has to be controlled for the Yoga, both in Pravrutti and Nivrutti. In Pravrutti, you can derive peace as happiness directly from the stored inert energy due to the control of expenditure. But in Nivrutti, you have to spend the entire inert energy without any control in the divine mission of God. In Nivrutti, since God, who is beyond the inert energy, is the source of happiness, you need not worry about its expenditure.

But in Nivrutti, the expenditure must be for God alone and not for the world. Hence, the control of worldly expenditure is also advised in the Yoga of Nivrutti by Patanjali (Yogah chittavrutti nirodhah). The Yoga Sutras of Patanjali keep the Lord or Ishwara as the goal and hence the Yoga of Patanjali is not the Yoga of Pravrutti for atheists, which is the Nirisvarasankhyayoga of Kapila (sage not the human incarnation).