Say seven times:

حَسْبِيَ اللَّهُ لَا إِلَهَ إِلَاّ هُوَ عَلَيْهِ تَوَكَّلْتُ وَهُوَ رَبُّ الْعَرْشِ الْعَظِيْمِ

HasbiyAllahu laa 'ilaaha 'illaa Huwa 'alayhi tawakkaltu wa Huwa Rabbul-'Arshil-'Adheem.

Allah is Sufficient for me, none has the right to be worshipped except Him, upon Him I rely and He is Lord of the exalted throne. Abu al-Darda’ (RA) said: if anyone says these dua seven times morning and evening, Allah will be sufficient for him against anything which grieves him, whether he is true or false in (repeating) them.

Reference: Sahih Maquf (Shu'aib and Arnaut). Abu Daud: 5081