What is the reason for feeling no pangs of conscience after committing a sin, and how can one overcome repeatedly returning to disobedience after repentance, and what is the way to avoid feeling despair about the acceptance of repentance?

All human beings err, and not regretting a sin is persistence [in it]. Persistence in minor sins makes them major ones. Therefore, sincere repentance (Tawbah Nasuhah) and regret for all sins are obligatory, along with feeling the greatness of Allah and His wrath, and being wary that sins may strip away blessings. One must sincerely turn to Allah, asking Him for sincere repentance, and not surrender to the whispers of Satan and procrastination. Among what aids in repentance is bringing to mind the disastrous consequences of sins, as mentioned by Ibn Al-Qayyim in "Al-Da' wal-Dawa'."