NBS 60

śānti-rūpāt paramānanda-rūpāc ca
Translation: 

Furthermore, bhakti is the embodiment of peace and supreme ecstasy.

Purport: 

This sūtra is further proof that bhakti is the best process for spiritual advancement. Lord Kṛṣṇa's personal form, name, and varied activities attract His devotees, who experience a love filled with śānti (peace) and paramānanda (supreme ecstasy). Indeed, the very nature of bhakti is peace and happiness.

In the Bhagavad-gītā, Lord Kṛṣṇa tells us who is eligible for śānti:

bhoktāraṁ yajña-tapasāṁ sarva-loka-maheśvaram
suhṛdaṁ sarva-bhūtānāṁ jñātvā māṁ śāntim ṛcchati

"One in full consciousness of Me, knowing Me to be the ultimate beneficiary of all sacrifices and austerities, the Supreme Lord of all planets and demigods, and the benefactor and well-wisher of all living entities, attains peace from the pangs of material miseries" (Bg. 5.29).

Śrīla Prabhupāda calls this verse "the peace formula," the sure method for achieving both individual and collective tranquillity. When people who temporarily control some property ignore the Lord's proprietorship over all that be and claim that they themselves are the sole proprietors and enjoyers of the world, and when people in positions of leadership claim to be the best friends of their dependents but fail to give them a chance to acquire transcendental knowledge, then the result is not peace but agitation, chaos, and war. Peace comes when we recognize Lord Kṛṣṇa as the supreme ruler, proprietor, and friend.

Regarding happiness, Śrīla Rūpa Gosvāmī defines three types: "(1) happiness derived from material enjoyment, (2) happiness derived by identifying oneself with the Supreme Brahman, and (3) happiness derived from Kṛṣṇa consciousness" (The Nectar of Devotion, p. 10). Rūpa Gosvāmī's conclusion is that happiness derived from pure bhakti is the highest because it is eternal, whereas material enjoyment and even oneness with Brahman are bound to be disrupted. Happiness in devotional service is open to all, but those who try to increase their own importance cannot know the sweet taste of Kṛṣṇa consciousness. Happiness comes not by trying to be the master but by becoming the servant of the servant of the supreme master [Cc. Madhya 13.80]. While praying to the Supreme Lord for relief from his suffering, Gajendra praised the happiness of the devotees:

Unalloyed devotees, who have no desire other than to serve the Lord, worship Him in full surrender and always hear and chant about His activities, which are most wonderful and auspicious. Thus they always merge in an ocean of transcendental bliss. Such devotees never ask the Lord for any benediction. [SB 8.3.20]