Shaykh Muhammad bin Sālih Al-'Uthaymīn رحمه الله stated:
From the means of removing the hardness of the heart is abundant remembrance of Allāh. Therefore remember Allāh abundantly. There's no difficulty in remembering Allāh because that which moves is the tongue and two lips.
Allāh has said: Certainly with the remembrance of Allāh the hearts are at ease.