Sankaracarya's Vivekachudamani 400

समाहितायां सति चित्तवृत्तौ

परात्मनि ब्रह्मणि निर्विकल्पे ।

न दृश्यते कश्चिदयं विकल्पः

प्रजल्पमात्रः परिशिष्यते यतः ॥

samāhitāyāṃ sati cittavṛttau

parātmani brahmaṇi nirvikalpe |

na dṛśyate kaścidayaṃ vikalpaḥ

prajalpamātraḥ pariśiṣyate yataḥ ||

(Sankaracarya's Vivekachudamani 400)

When the functions of the mind, the thoughts, have merged in the Paramatma, the Brahman, the Absolute, then this phenomenal world is perceived no longer. What remains thereafter is all mere talk.

"It is quite evident that you are feeling anxiety in your mind. The best way to overcome this, the way to control the mind is to become a pure devotee of the Lord. This is stated in the Bhagavad Gita in the sixth chapter, that one has to control the mind otherwise the mind will become his worst enemy.

Fix your mind on Lord Hriskesa who is Paramatma, Brahman and the Bhagavan then you will experience peace of mind and your mind will be your best friend.