Rasulullah (Sallallaho alihe wasallam) said, "One who is too weak to bear the strain of keeping awake at night (in the worship of Almighty Allah), is too miserly to spend his wealth in the path of Allah and is too cowardly to take part in jihaad is advised to remain engaged in the zikr of Allah."
This hadith should shame 99% of Muslims as we read the words of Allah's most perfect servant.
This shows that deficiencies in respect of non-obligatory form of worship can be atoned through profuse zikr of Almighty Allah. Hadhrat Anas (RA) reported that Rasulullah, PBUH, had said, "Zikr of Allah is a sign of Imaan and it ensures exemption from hypocrisy, and provides a safeguard against the devil and protection from the fire of hell." Because of all these benefits, zikr has been regarded more virtuous than many other forms of worship; it is specially effective in providing protection against the Devil. It is stated in one hadith that the Devil in a a kneeling position, clings to the heart of a man and when the man remembers Almighty Allah, the devil becomes helpless and frustrated and therefore draws back, but whenever he finds the man neglecting it, he pollutes the heart with evil thoughts.
May Allah protect us from this and may we all practice zikr regularly and often. Ameen!