Revatīnandana: Purport: "When a person is fully engaged in the transcendental loving service of the Lord, he is pleased in himself, and thus he is no longer engaged in sense gratification or in fruitive activities. Otherwise, one must be engaged in sense gratification, since one cannot live without engagement."
Prabhupāda: Yes, that is the point. We must have engagement. We cannot stop. The same example: you cannot stop a child working, or in activities. By nature we are living entities; we must act. It is not possible to stop activities. So just like it is said, "An idle brain is a devil's workshop," so if we have no good engagement, then you will have to engage yourself in something nonsense.
Just like child, if he's not engaged in education, he becomes a spoiled child. Similarly, our two business: either material sense gratification or Kṛṣṇa consciousness, or bhakti-yoga or yoga. So if I am not in yoga system, then I must be in sense gratification. And if I am in sense gratification, there is no question of yoga.