A devotee becomes mad in his ecstasy of love for Kṛṣṇa.
(Teachings of Lord Caitanya).

If one does not take shelter of Kṛṣṇa's lotus feet, he falls down (patanty adhaḥ), even from liberation. The Hare Kṛṣṇa mahā-mantra, however, gives liberation and at the same time offers shelter at the lotus feet of Kṛṣṇa. If one takes shelter at the lotus feet of Kṛṣṇa after liberation, he develops his dormant ecstatic love for Kṛṣṇa. That is the highest perfection of life.
(Sri Caitanya Caritamrta---3:3:257---purport).

In the beginning one has to discharge devotional service according to regulative principles, but gradually, as devotional service becomes one's life and soul, one achieves the most exalted position of ecstatic love for Kṛṣṇa. Ultimately, Kṛṣṇa is the goal of life.
(Sri Caitanya Caritamrta---3:4:70---purport).

Feeling separation from Kṛṣṇa and engaging in the service of the Lord to fulfill His mission constitute the best example of love of Kṛṣṇa.
(Sri Caitanya Caritamrta---2:4:178---purport).

A devotee who has developed a genuine love for Kṛṣṇa can always see Him everywhere, whereas a demon, not having a clear understanding of the Supreme Lord, cannot see Him.
(Srimad Bhagavatam---7:8:12---purport).

He who has love for Kṛṣṇa has attained the topmost liberation.
(Sri Caitanya Caritamrta---2:8:249---purport).

By chanting the Hare Kṛṣṇa mantra without offenses, one increases his love for Kṛṣṇa.
(Srimad Bhagavatam---6:3:24---purport).

It is natural for those who have developed intense love for Kṛṣṇa not to care for personal inconvenience and impediments. Such devotees are simply determined to execute the order of the Supreme Personality of Godhead or His representative, the spiritual master.
(Sri Caitanya Caritamrta---2:4:186---purport).

Just as liquid sugar juice progresses from one stage to another, similarly transcendental love for the Supreme Lord develops by stages.
When one actually becomes situated on the transcendental platform, he becomes steady.
(Teachings of Lord Caitanya).