Ibn al Qayyim (رحمه الله) said:
The following treatments consist of fifteen types of remedies, if they do not overwhelm the ailment of anxiety, sorrow and grief, then indeed it has developed into an acute form, and its causes have been firmly established, it would need to be uprooted entirely.
The First: Monotheism of Lordship.
The Second: Monotheism of Worship.
The Third: Monotheism of Knowledge and Belief(Monotheism of Allaah’s Names and Attributes)
The Fourth: Glorifying and freeing/absolving the Lord from the notion that He may oppress His slave, or punish him for no reason that would necessitate that.
The Fifth: The Servant acknowledging that he himself is the oppressor.
The Sixth: Invoking Allah with the most beloved of things; His Names and Attributes; and from the most comprehensive of them in gathering the meanings of the Names and Attributes is: Al-Hayy, al-Qayyoom.
The Seventh: Seeking Isti’aana (assistance) from Him alone.
The Eighth: Affirming one’s hope in Allah.
The Ninth: Truly realizing Tawakul (trust) in Him, and leaving the affair with Him. Acknowledging that all your affairs are in His Hands; He does with them what He wills, that His decision concerning them will come to pass, His judgment concerning them is just.
The Tenth: To Immerse one’s heart in the gardens of the Quran, and to make it (the Quran) for the heart, as spring is for animals. To use it for illumination in the darkness of doubts and desires, to take comfort in it from everything one missed, to gain support from it in every calamity, to seek remedy from it from all the diseases of the heart; so it becomes the purging of sorrow and the healing of anxiety and grief.
The Eleventh: Practicing Istighfar (saying Astaghfirulah – I seek forgiveness from Allah).
The Twelfth: Practicing Tawbah (repentance).
The Thirteenth: To strive .
The Fourteenth: Salat (prayer)
The Fifteenth: Negating and freeing oneself from ability and strength and putting that in the Hands of the One who owns them.