Imam Khomeini in this regard has undertaken very serious discussions in his famous book "an exposition on Forty Hadith" as following:
Though this world is not where one is immediately rewarded, yet faithfulness to God and abstaining from sins is fruitful in this world also.
God never entrusts His creatures with cumbersome and heavy tasks, which are beyond their powers, but it is the Satan and his allies who magnify them in your view.
God forbid, if there are any lapses on your part, ask God’s forgiveness, and beseechingly implore Him that you will be more careful in future, so that the Almighty may throw open the doors of His grace and compassion to you, and may guide you in the straight path.
I hope, that Satan will be driven away, and the Divine forces will prevail.
I assure you that this practice of self-criticism and self-examination would not hinder your day-to-day activity.
I advise you to remain in the same state of mind till night-the time for introspection and inner deliberation-and evaluate your deeds of the whole day.
Imam further explains that this is the time to see whether you have been honest to the Giver of all, to whom everybody is accountable. If you have been faithful to Him, you should be thankful to Him, that He has made you successful in your intentions.
And realize that you have gone a step forward in His direction and became an object of His attention.
God willing, God will help you in performing all worldly and religious duties, and will diminish your pains for the next day.
If you repeat this many times, it is imminent that you will be accustomed to the acts of piety. You will see then that all this does not require you to make hard efforts.
Read more:
IMAM KHOMEINI RECOMMENDS FAITHFUL PEOPLE TO UNDERTAKE ESTIMATION AND EVALUATION OF VIRTUES