Bhagavad Gita

ಯತತೋ ಹ್ಯಪಿ ಕೌಂತೇಯ ಪುರುಷಸ್ಯ ವಿಪಶ್ಚಿತಃ ।
ಇಂದ್ರಿಯಾಣಿ ಪ್ರಮಾಥೀನಿ ಹರಂತಿ ಪ್ರಸಭಂ ಮನಃ ॥೬೦॥
yatato hyapi kauṃteya puruṣasya vipaścitaḥ |
iṃdriyāṇi pramāthīni haraṃti prasabhaṃ manaḥ ||60||

Gist of the sloka:
Even when the seeker makes great efforts in learning the right path; senses can forcibly disturb the mental equilibrium and take it away from the path.
Even after reading and listening for many years, the path to salvation is not easy. Without the determination and persistence, it’s not even conceivable to be on the path. One should therefore, be brave and be mentally determined. If the mind is not determined, the senses would be completely free. One should not get into the states of desire, disappointment, fear or anger. One should control the life [actions, thoughts etc.,]. Even after realizing the truth of the sacred books, the senses continue to threaten. They create doubts, give numerous reason why to postpone or leave the path. These happen to every seeker.
Even when this appears to be impossible to conquer, Lord Krishna gives very simple solution in the next verse.