Ibn Al-Qayyim said, “Opposing desires will allow the servant to acquire strength in his body, his heart, and his speech. Some of the righteous predecessors would say that conquering desires needs more strength than one who could conquer a city by himself.”
Source: Rawḍat al-Muḥibbīn 1/477
قال ابن القيم رحمه الله مُخَالَفَةُ الْهَوَى تُورِثُ الْعَبْدَ قُوَّةً فِي بَدَنِهِ وَقَلْبِهِ وَلِسَانِهِ وَقَالَ بَعْضُ السَّلَفِ الْغَالِبُ لِهَوَاهُ أَشَدُّ مِنْ الَّذِي يَفْتَحُ الْمَدِينَةَ وَحْدَهُ
1/477 روضة المحبين
Source: Daily Hadith