Our loving propensity expands just as a vibration of light or air expands, but we do not know where it ends. The Nectar of Devotion teaches us the science of loving every one of the living entities perfectly by the easy method of loving Kṛṣṇa. We have failed to create peace and harmony in human society, even by such great attempts as the United Nations, because we do not know the right method. The method is very simple, but one has to understand it with a cool head. The Nectar of Devotion teaches all men how to perform the simple and natural method of loving Kṛṣṇa, the Supreme Personality of Godhead. If we learn how to love Kṛṣṇa, then it is very easy to immediately and simultaneously love every living being. It is like pouring water on the root of a tree or supplying food to one's stomach. The method of pouring water on the root of a tree or supplying foodstuffs to the stomach is universally scientific and practical, as every one of us has experienced.
(Nectar of Devotion).

In the Bhagavad-gītā the Lord clearly says that persons who are engaged in His devotional service without adulteration are situated in Brahman. Actual Brahman realization means Kṛṣṇa consciousness and engagement in devotional service. The devotees are therefore real brahmacārīs because their activities are always in Kṛṣṇa consciousness, devotional service.The Kṛṣṇa consciousness movement therefore issues a supreme call to all kinds of religionists, asking them with great authority to join this movement, by which one can learn how to love God and thus surpass all formulas and formalities of scriptural injunction. A person who cannot overcome the jurisdiction of stereotyped religious principles is compared to an animal chained up by his master. The purpose of all religion is to understand God and develop one's dormant love of Godhead.
(Krsna Book).

Therefore, one need not undergo severe penances for many thousands of years; one need only learn how to love Kṛṣṇa and be always engaged in His service (sevonmukhe hi jihvādau svayam eva sphuraty adaḥ (Brs. 1.2.234)). Then one can very easily go back home, back to Godhead. Instead of bringing the Lord here for some material purpose, to have a son or whatever else, if we go back home, back to Godhead, our real relationship with the Lord is revealed, and we eternally engage in our eternal relationship. By chanting the Hare Kṛṣṇa mantra, we gradually develop our eternal relationship with the Supreme Person and thus attain the perfection called svarūpa-siddhi. We should take advantage of this benediction and go back home, back to Godhead. Śrīla Narottama dāsa Ṭhākura has therefore sung, patita-pāvana-hetu tava avatāra: Caitanya Mahāprabhu appeared as an incarnation to deliver all fallen souls like us and directly bestow upon us love of Godhead. We must take advantage of this great benediction of the great Personality of Godhead.
(Srimad Bhagavatam------10:3:37-38-------purport).

In the Bhagavad-gītā Kṛṣṇa has taught the philosophy of surrender to the Supreme Personality of Godhead. One who has surrendered to the Supreme can make further progress by learning to love Him. Therefore the Kṛṣṇa consciousness movement propagated by Lord Caitanya is especially meant for those who are cognizant of the presence of the Supreme Godhead, the ultimate controller of everything. His mission is to teach people how to dovetail themselves into engagements of transcendental loving service. He is Kṛṣṇa teaching His own service from the position of a devotee. The Lord's acceptance of the role of a devotee in the eternal form of Lord Śrī Caitanya Mahāprabhu is another of the Lord's wonderful features. A conditioned soul cannot reach the absolute Personality of Godhead by his imperfect endeavor, and therefore it is wonderful that Lord Śrī Kṛṣṇa, in the form of Lord Gaurāṅga, has made it easy for everyone to approach Him.
(Sri Caitanya Caritamrta------1:4:41------purport).

However, one should generally accept the following principles to properly execute devotional service: (1) take shelter of a bona fide spiritual master, (2) receive initiation from the spiritual master, (3) serve the spiritual master, (4) inquire and learn love from the spiritual master, (5) follow in the footsteps of holy persons devoted to the transcendental loving service of the Lord, (6) prepare to give up all kinds of enjoyment and miseries for the satisfaction of Kṛṣṇa, (7) live in a place where Kṛṣṇa had His pastimes, (8) be satisfied by whatever is sent by Kṛṣṇa for the maintenance of the body and hanker for no more, (9) observe fasting on Ekādaśī day (this occurs on the eleventh day after the full moon and the eleventh day after the new moon.
(Teachings of Lord Caitanya).