By Sayyidi Habib Umar bin Hafiz (may Allah protect him and benefit us by him)
Any action which is heavy and hard upon the lower self (nafs) will be weighty when your good deeds are weighed on the Scales on the Day of Judgement. Any action which is easy for the lower self will be light upon the Scales.
When someone’s soul becomes tranquil (al-nafs al-mutma’inah), however, they no longer find any hardship or difficulty in acts of obedience.
The Messenger of Allah ﷺ said that good character is the heaviest thing that can be placed on the Scales. This is due to the fact that showing good character is difficult for the lower self.
Any act of disobedience which you make light of will be weighty when your bad deeds are weighed on the Scales. Any act of disobedience which you see as being great and regret performing will be light on the Scales.