Revatīnandana: "Verse 24: One whose happiness is within, who is active within, and who rejoices within, and is illumined within is actually the perfect mystic. He is liberated in the Supreme and ultimately he attains the Supreme (BG 5.24)."
Prabhupāda: Within. Within means self-satisfied. Bhakti... How this process can give you that understanding within? How? One may question that "How it is possible within?" Yes, it is possible. The example is given by Gosvāmīs that just like a hungry man, he wants some food, he's demanding some food, and if you give him nice food he eats, and with each morsel of food he realizes within that "I am eating. I am getting strength. I am satisfied." Is it not? Similarly, you begin this Kṛṣṇa consciousness chanting. You will feel yourself, "Yes. Yes, I am doing something. Yes, I am eating something. Yes, I am getting spiritual strength." Is it not a fact? Actually, if somebody is disturbed, then it is to be understood that his disease is little more acute. Otherwise, in normal condition, if he chants and follows the regulation, then he will feel, "Yes, I am doing something. I am getting something. I am getting strength. I am getting satisfaction. I am feeing I am spiritually advancing." These things will manifest automatically simply by chanting.
Revatīnandana: "Verse 25: One who is beyond duality and doubt, whose mind is engaged within, who is always busy working for the welfare of all sentient beings, and who is free from all sins achieves liberation in the Supreme (BG 5.25)."
Prabhupāda: Now, these things are very important things, "whose mind is engaged within, who is always busy working for the welfare of all sentient beings." This chanting of Hare Kṛṣṇa, it is welfare work for all sentient being, even the worms, the microbes, the cockroaches. So many living entities are within this room. By hearing this vibration of Hare Kṛṣṇa mantra they will be getting also the result. That is described in Caitanya-caritāmṛta. When Lord Caitanya questioned Haridāsa Ṭhākura about the efficacy of chanting, how he described? You will find it in the Teachings of Lord Caitanya. It is a fact. If you are chanting within this room and if you find nobody is coming to participate in the kīrtana, don't be disappointed. There are many germs, worms, cockroaches, within this room—they are being benefited. They are being benefited. You cannot find any place without any living entities. You just find out one hole. You will see, hundreds of ants are coming out. So living entities are in the air, in the water, in the holes, everywhere. And this vibration... Everyone, every living, entity has got his ear. So this sound is so powerful because it is spiritual that it will act even on the ants and the trees and birds and the bees, what to speak of human being. It is so nice thing. So those who are chanting... "One who is always busy working."
What is the busyness of these Kṛṣṇa conscious students? They are busy in chanting Hare Kṛṣṇa, in distributing knowledge in Kṛṣṇa consciousness. Therefore they are doing the best welfare work in the world. Other welfare work will be finished as soon as this body is finished.