When does sex become lust?

The following is an excerpt from a samvaad (dialogue) session with Acharya Prashant.

Question: We treat sex as fun, as food, and nothing more than that. Is that why sex converts into lust?

Acharya Prashant: No, wrong. We do not treat sex just as fun and as food. Our longing for sex is far more intense, far more aggressive, far more meaningful, rather loaded with meaning, than is our desire…