What is the happiness a person feels after repentance?

Sincere repentance motivates its doer to return to Allah, engage in obedience, distance himself from disobedience, and increases faith. The happiness felt by the repentant is the good life that Allah promised to those who perform righteous deeds, as stated in His Almighty saying: "Whoever does righteousness, whether male or female, while he is a believer - We will surely cause him to live a good life." This good life is living in obedience to Allah and staying away from His disobedience, which brings happiness and tranquility to the heart. As for turning away from the remembrance of Allah, it leads to a constricted life, as stated in His Almighty saying: "And whoever turns away from My remembrance - indeed, he will have a constricted life."