How do acts of worship (prayer, fasting, zakat) contribute to treating states of stress, anxiety, and depression?

The servant who unifies Allah Almighty and submits to His law is the happiest and most tranquil of people, for he knows his purpose and his destiny. As Ibrahim ibn Adham said: "If kings and sons of kings knew what we are in, they would fight us for it with swords."

Prayer, Zakat, and Fasting have a great impact on the heart's tranquility and serenity: - Prayer: It brings serenity, tranquility, and comfort to the heart. - Zakat: Whoever pays it willingly will find comfort and serenity, and worry will not find its way to his heart. - Fasting: The believer's soul finds tranquility, and distress and whispers depart from it, because it is for Allah Almighty, and Allah has singled it out for Himself: "Every deed of the son of Adam is for him, except fasting, for it is for Me and I shall reward for it."