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]. Krsna 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 Krsna 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 Krsna. Then your life is perfect.

From Srila Prabhupada’s lecture on Bhagavad-gita 1.15 — London, July 15, 1973