‘Ubadah ibn Saamit related that he heard the Messenger of Allah (Blessings and Peace be upon him) say:
"Persist in fighting in the way of Allah, for it is among the doors of Paradise. Through it, Allah removes anxiety and worry."
The effect that fighting in the way of Allah has upon a person is something that we might not accept, but it is something that our conscience accepts. Whenever the soul avoids combating evil, its level of fear and anxiety increase. But if it fights for the sake of Allah, Allah will transform fear and anxiety into happiness, strength, and vigor.
(Fight against them so that Allah will punish them by your hands and disgrace them and give you victory over them and heal the breasts of a believing people, and remove the anger of their [believers’] hearts.) (Qur’an 9: l4-l5)
Therefore fighting in the way of Allah is one of the most potent remedies for combating anxiety, grief, and worry; and to Allah do we turn for help.