Hakeemul Ummah Hazrat Moulana Ashraf Ali Thaanwi Sahib رحمه الله has said that Mujaahadah, i.e. striving against the dictates of the Nafs does not eliminate natural propensities. However, after Mujaahadah the task of restraining the Nafs from the commission of evil is simplified. Constant Mujaahadah erodes the strength of the Nafs, hence its dictates and desires are vastly weakened. It is mentioned in the Hadīth;
وإذا سمعتم برجل تغير عن خلقه فلا تصدقوا به ( مسند أحمد ط الرسالة الرقم 27499)
“When you hear someone has eliminated his natural propensity, do not acknowledge it.”
(SOURCE: MALFOOZAAT OF HAZRAT MOULANA ASHRAF ALI THAANWI SAHIB رحمه الله, PART 6)