"The ego (nafs) is the lowest dimension of man's inward existence, his animal and satanic nature. There are two kinds of people, one are those whose Nafs have overcome them and led them to ruin because they yielded to them and obeyed their impulses. The other kinds are those who have overcome their Nafs and made them obey their commands."
When your evil side, bad qualities or your negative self is predominant over your good side, it overshadows, your good actions, that is the stage of the unpurified Nafs. The Nafs n its unrefined state, "the ego (nafs) is the lowest dimension of man's inward existence, his animal and satanic nature." what follows this unpurified Nafs(Ego) is a dirty heart, at this point it is more pleasing and easier to do bad or evil upon yourself and others, doing what you want, and to follow your own passion.
"Verily never will Allah change the condition of a people until they change it themselves (with their own souls)." - Quran 13:11 Surah Ar-Rad(The Thunder)
The unpurified Nafs the ego must be "broken down"
A few ways to break the nafs(ego) is by attacking & humiliating your nafs, pushing yourself, controlling yourself, until you become a new person. A few examples of the characteristic of the nafs is anger, pride, envy, jealousy, lust, backbiting etc...To become a new person, all these bad qualities must be completely destroy, controlled or eliminated, in order to rebuild yourself again.
The Most Beloved Prophet (Salla Allahu ta'ala alayhi wa Sallam), said to his companions returning from a battle:"You have returned from a smaller battle to a greater battle." He was then asked by the companions, "What can be a greater battle than that we have just fought?" He (Salla Allahu ta'ala alayhi wa Sallam), answered,"The battle against one's nafs".
The Cleaning Of The Heart
The dhikr (remembrance) of Allah being a polish for the heart
Sayyiduna ‘Abdullah ibn ‘Umar (radiyallahu’anhuma) reports that Rasulullah (sallallahu ‘alayhi wasallam) said:
Indeed the hearts rust just as iron does. The Sahabah (radiyallahu’anhum) asked: “What is its polish?”
Sayyiduna ‘Abdullah ibn ‘Umar (radiyallahu ‘anhuma) reports that Rasulullah (sallallahu ‘alayhi wasallam) said:
There is a polish for everything that takes away rust: and the polish for heart is the remembrance of Allah.