Bg 18.33

dhrtya yaya dharayate
manah-pranendriya-kriyah
yogenavyabhicarinya
dhrtih sa partha sattviki

Word for word: 
dhrtya — determination; yaya — by which; dharayate — one sustains; manah — of the mind; prana — life; indriya — and senses; kriyah — the activities; yogena — by yoga practice; avyabhicarinya — without any break; dhrtih — determination; sa — that; partha — O son of Prtha; sattviki — in the mode of goodness.

Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
O son of Prtha, that determination which is unbreakable, which is sustained with steadfastness by yoga practice, and which thus controls the activities of the mind, life and senses is determination in the mode of goodness.

Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Yoga is a means to understand the Supreme Soul. One who is steadily fixed in the Supreme Soul with determination, concentrating one’s mind, life and sensory activities on the Supreme, engages in Krishna consciousness. That sort of determination is in the mode of goodness. The word avyabhicarinya is very significant, for it indicates that persons who are engaged in Krishna consciousness are never deviated by any other activity.