The best remedy for anxiety is remembrance of Allaah (dhikr), and regularly praying on time, and avoiding too much free time. 

Allaah says concerning dhikr (interpretation of the meaning): 

“Those who believed (in the Oneness of Allaah — Islamic Monotheism), and whose hearts find rest in the remembrance of Allaah verily, in the remembrance of Allaah do hearts find rest”

al-Ra’d 13:28 

and He says (interpretation of the meaning): 

“And We send down of the Qur’aan that which is a healing and a mercy to those who believe (in Islamic Monotheism and act on it)”

al-Isra’ 17:82 

“O mankind! There has come to you a good advice from your Lord (i.e. the Qur’aan, enjoining all that is good and forbidding all that is evil), and a healing for that which is in your breasts, — a guidance and a mercy (explaining lawful and unlawful things) for the believers”

Yoonus 10:57 

And He said concerning prayer (interpretation of the meaning): 

“Verily, man (disbeliever) was created very impatient;

Irritable (discontented) when evil touches him;

And niggardly when good touches him.

Except those who are devoted to Salaah (prayers).

Those who remain constant in their Salaah (prayers)”

al-Ma’aarij 70:19-23 

“O you who believe! Seek help in patience and As-Salaah (the prayer). Truly, Allaah is with As-Saabiroon (the patient)”

al-Baqarah 2:153 

When something distressed the Prophet (peace and blessings of Allaah be upon him) he would turn to prayer (Narrated by Ahmad and Abu Dawood, 1319; classed as hasan by al-Albaani in Saheeh al-Jaami’ no. 4703). 

And he used to say: “O Bilaal, give the call to prayer (iqaamah) and let us find rest in it.” Narrated by Ahmad, and Abu Dawood; classed as saheeh by al-Albaani in Saheeh al-Jaami’, no. 7892. 

Prayer brings comfort to the heart and is a delight, and is a remedy for worry and grief. 

Free time leaves the door open to bad thoughts and the distress, worry and anxiety that result from them.                          

Whenever you feel anxious and worried, hasten to do wudoo’ and pray, and read Qur’aan, and keep yourself busy with beneficial actions, especially the dhikrs for morning and evening, and when going to sleep, eating, drinking, and entering and leaving the home. 

The Muslim who believes in the will and decree of Allaah should not worry about his provision or children or the future in general, because that was written before he came into existence. Rather he should worry about his sins and shortcomings before his Lord, the way of dealing with which is to repent and hasten to do good deeds. Allaah has guaranteed the believers a good life, as He says (interpretation of the meaning): 

“Whoever works righteousness — whether male or female — while he (or she) is a true believer (of Islamic Monotheism) verily, to him We will give a good life (in this world with respect, contentment and lawful provision), and We shall pay them certainly a reward in proportion to the best of what they used to do (i.e. Paradise in the Hereafter)”

al-Nahl 16:97. 

For more information see question no 22704 and 21677. 

And Allaah knows best.

Islam Q&A