Jayapataka Swami
Even in the books of patanjali yoga, it is said that in order to attain perfection in yoga one needs Hari-bhakti. Ultimately devotion is the perfection. Narayana Smriti at the end of one's life is perfection. Normally people end their life thinking of whatever their attached to. If we are chanting the Lord's names and engage in his service then we maintain an attachment for the Lord throughout our life. The Lord will be the common denominator and pivot point in our different activities. Whatever process one is engaging in, this remembrance of Narayana, taking shelter of the Lord is the most important aspect.
Lord Chaitanya
Regardless of time or place, one who chants the holy name, even while eating or sleeping, attains all perfection.
A.C. Bhaktivedanta Swami Prabhupada
Even by fighting, you can be a great devotee, just like Arjuna. He was not chanting on the beads, but he was fighting. But still, bhakto ‘si priyo ‘si me [Bg. 4.3]. Krishna says, “Oh, you are My great devotee.” Now people, may say that “He was not chanting. He was fighting. How he became a great devotee?” But Krishna says, bhakto ‘si priyo ‘si me: “You are My dear friend. You are My devotee. Because you are utilizing your energy for Me.” So bhakti means you utilize your energy for Krishna. Then your life is perfect.
Lecture on Bhagavad-gita 1.15 — London, July 15, 1973
Bhakti Vikas Swami
Under the guidance of the brahmanas in the varnasrama society, anyone performing work according to that can attain all perfection, by engaging his proclivity in the service of Krishna: sva karmana tam abhyarca siddhim vindati manavah. By worshiping the Supreme Lord by performance of their work, then everyone can achieve perfection.
Lecture on SB 3.6.32 – About the Four Varnas – Vyasa Puja 2008 – 5th Jan'08 – Tirupati
A.C. Bhaktivedanta Swami Prabhupada
The wise inhabitants of the heavenly regions know that the perfection of the head is to offer obeisances to the Supreme Lord, the perfection of the life-breath is to worship the Lord, the perfection of the mind is to ponder the details of His transcendental qualities, and the perfection of speech is to chant the glories of His qualities.
A.C. Bhaktivedanta Swami Prabhupada
The spiritual master's order should be taken as the prime duty of life. If one gets a bona fide spiritual master and acts according to his direction, then his perfection of life in Krishna Consciousness is guaranteed.