An interesting analogy given by my Sheikh Hazrat Maulana Yunus Patel Saahib (db).....
If there is heavy mist on the windscreens of our cars, then we de-mist those windscreens when driving. If we do not do so, then we are liable to meet with an accident. In a like manner, when our hearts become misted with sins, with evil desires and passions, it becomes necessary to de-mist our hearts with Tawbah and Istighfaar (repentance).
According to a Hadith of Rasulullah (Sallallaahu Alayhi Wasallam) , everything rusts according to its nature, and the hearts rust with worldly desires and sins. Zhikr (Praise of Allah Ta'ala) removes the rust of the (spiritual) heart - it purifies and cleanses the heart.
If we do not de-mist our hearts of evils like malice, greed, pride, jealousy, anger, etc., then we will be always causing accidents in society.
The easiest way to obtain purification of the heart and soul is to spend time in the company of the Ahlullah (Friends of Allah Ta'ala) (the people of Allah) - those who have already purified themselves.
"There is nothing more beneficial to a Muslims heart than to mix with the righteous and to watch their actions, while nothing is more harmful to the heart than mixing with the sinners and watching their actions. - Imaam Ahmad ibn Harb (rahimahullâh)