It has been tried and proven that if a person applies himself to shemiras halashon, the more he grows accustomed to it, the easier it becomes. He will begin to notice the improper words that leave his mouth, whereas he had previously taken no notice, due to his habit of speaking as he pleased. After breaking the habit of lashon hara, with the just a slight effort, he can refrain from speaking forbidden words. ~ Chofetz Chaim zt”l