CC Madhya 24.181
dhṛtiḥ — endurance; syāt — may become; pūrṇatā — fullness; jñāna — knowledge of the Supreme Personality of Godhead; duḥkha-abhāva — the absence of misery; uttama-āptibhiḥ — by attainment of the highest platform of perfection; aprāpta — not obtained; atīta — gone; naṣṭa — destroyed; artha — object, goal; anabhisaṁśocana — absence of lamentation; ādi — and so on; kṛt — doing.
“ ‘Dhṛti is the fullness felt due to the absence of misery and the attainment of knowledge of the Supreme Lord and pure love for Him. The lamentation that accrues from not obtaining a goal or from losing something already attained does not affect this completeness.’
This verse is found in the Bhakti-rasāmṛta-sindhu (2.4.144).