Bhagavad Gita Chapter 3, Verse 43

एवं बुद्धेः परं बुद्ध्वा संस्तभ्यात्मानमात्मना | जहि शत्रुं महाबाहो कामरूपं दुरासदम् ||

evaṁ buddheḥ paraṁ buddhvā saṁstabhyātmānam ātmanā jahi śatruṁ mahābāho kāma-rūpaṁ durāsadam

Thus, knowing Him (the Self) as superior to the intellect, and steadying the self by the Self, slay the enemy, O mighty-armed one, in the form of desire, difficult to conquer.

Krishna concludes Chapter 3 with the secret of conquering desire. Know yourself as buddheḥ param—the Self beyond intellect. From there, steady the mind through saṁstabhyātmānam ātmanā—using pure awareness to control the restless self. Then slay kāma-rūpam, desire itself. Why does this work when willpower fails? Because you're not fighting desire from within it (impossible), but watching it from beyond (durāsadam—difficult, but possible from Self-awareness).