Source: Srimad Bhagavatham : Its Message for the Modern Man by Swami Shantananda Puri Maharaj
We should not be unduly worried about and dwell constantly on the elimination of our defects like passion, desires, anger, greed. By going on filling up our Chitta with constant remembrance of God or Self and taking Lord's name constantly, they will seep and saturate our heart in and around and by the sheer weight strangle all the Vasanas (latent tendencies) by throttling them to natural death.
Please check these: Excerpts from a discourse by our Sri Sri Muralidhara Swamiji
If we put some ant-repellant around the sweets, the ants cannot get inside to the sweets. Similarly, lust, anger and fear would constantly pester our mind. We cannot avoid the attack of these on our mind by our intelligence.
Don't worry. Just like hunger and thirst, lust is also inborn. No doubt, we have to overcome it. But it is not as easy as we think. It will not be gone one fine morning. It will happen slowly and will take time. Constant prayers and chanting will help this happen
Just as soap cleanses the cloth of its impurities, so also the mantra is a spiritual soap cleansing the mind. Just as fire cleanses gold of its impurities, so also mantra cleanses the mind of its impurities.