Śrī Caitanya Mahāprabhu has given us an authorized program for this purpose, centered around the chanting of the Hare Kṛṣṇa mantra. This chanting has so much power that it immediately attaches one to Kṛṣṇa. That is the beginning of sādhana-bhakti. Somehow or other, one has to fix his mind on Kṛṣṇa. The great saint Ambarīṣa Mahārāja, although a responsible king, fixed his mind on Kṛṣṇa, and similarly anyone who tries to fix his mind in this way will very rapidly make progress in successfully reviving his original Kṛṣṇa consciousness.
Now this sādhana-bhakti, or practice of devotional service, may also be divided into two parts. The first part is called service according to regulative principles: one has to follow these different regulative principles by the order of the spiritual master or on the strength of authoritative scriptures, and there can be no question of refusal. That is called vaidhi, or regulated. One has to do it without argument. Another part of sādhana-bhakti is called rāgānugā. Rāgānugā refers to the point at which, by following the regulative principles, one becomes a little more attached to Kṛṣṇa and executes devotional service out of natural love. For example, a person engaged in devotional service may be ordered to rise early in the morning and offer ārati, which is a form of Deity worship. In the beginning, by the order of his spiritual master, one rises early in the morning and offers ārati, but then he develops real attachment. When he gets this attachment, he automatically tries to decorate the Deity and prepare different kinds of dresses and thinks of different plans to execute his devotional service nicely. Although it is within the category of practice, this offering of loving service is spontaneous. So the practice of devotional service, sādhana-bhakti, can be divided into two parts—namely, regulative and spontaneous.
Rūpa Gosvāmī defines the first part of devotional practice, or vaidhi-bhakti, as follows: "When there is no attachment or no spontaneous loving service to the Lord, and one is engaged in the service of the Lord simply out of obedience to the order of the spiritual master or in pursuance of the scriptures, such obligatory service is called vaidhi-bhakti."
These principles of vaidhi-bhakti are also described in Śrīmad-Bhāgavatam, Second Canto, First Chapter, verse 5, where Śukadeva Gosvāmī instructs the dying Mahārāja Parīkṣit as to his course of action. Mahārāja Parīkṣit met Śukadeva Gosvāmī just a week before his death, and the King was perplexed as to what should be done before he was to pass on. Many other sages also arrived there, but no one could give him the proper direction. Śukadeva Gosvāmī, however, gave this direction to him as follows: "My dear King, if you want to be fearless in meeting your death next week (for actually everyone is afraid at the point of death), then you must immediately begin the process of hearing and chanting and remembering God." If one can chant and hear Hare Kṛṣṇa and always remember Lord Kṛṣṇa, then he is sure to become fearless of death, which may come at any moment.
In the statements of Śukadeva Gosvāmī it is said that the Supreme Personality of Godhead is Kṛṣṇa. Therefore Śukadeva recommends that one should always hear about Kṛṣṇa. He does not recommend that one hear and chant about the demigods. The Māyāvādīs (impersonalists) say that one may chant any name, either that of Kṛṣṇa or those of the demigods, and the result will be the same. But actually this is not a fact. According to the authorized version of Śrīmad-Bhāgavatam, one has to hear and chant about Lord Viṣṇu (Kṛṣṇa) only.
So Śukadeva Gosvāmī has recommended to Parīkṣit Mahārāja that in order to be fearless of death, one has to hear and chant and remember the Supreme Personality of Godhead, Kṛṣṇa, by all means. He also mentions that the Supreme Personality of Godhead is sarvātmā. Sarvātmā means "the Supersoul of everyone." Kṛṣṇa is also mentioned as īśvara, the supreme controller who is situated in everyone's heart. Therefore, if some way or other we become attached to Kṛṣṇa, He will make us free from all danger. In Bhagavad-gītā it is said that anyone who becomes a devotee of the Lord is never vanquished. Others, however, are always vanquished. "Vanquished" means that after getting this human form of life, a person does not come out of the entanglement of birth and death and thus misses his golden opportunity. Such a person does not know where he is being thrown by the laws of nature.
Suppose one does not develop Kṛṣṇa consciousness in this human form of life. He will be thrown into the cycle of birth and death, involving 8,400,000 species of life, and his spiritual identity will remain lost. One does not know whether he is going to be a plant, or a beast, or a bird, or something like that, because there are so many species of life. The recommendation of Rūpa Gosvāmī for reviving our original Kṛṣṇa consciousness is that somehow or other we should apply our minds to Kṛṣṇa very seriously and thus also become fearless of death. After death we do not know our destination, because we are completely under the control of the laws of nature. Only Kṛṣṇa, the Supreme Personality of Godhead, is controller over the laws of nature. Therefore, if we take shelter of Kṛṣṇa seriously, there will be no fear of being thrown back into the cycle of so many species of life. A sincere devotee will surely be transferred to the abode of Kṛṣṇa, as affirmed in Bhagavad-gītā.
In the Padma Purāṇa, also, the same process is advised. There it is said that one should always remember Lord Viṣṇu. This is called dhyāna, or meditation—always remembering Kṛṣṇa. It is said that one has to meditate with his mind fixed upon Viṣṇu. Padma Purāṇa recommends that one always fix his mind on the form of Viṣṇu by meditation and not forget Him at any moment. And this state of consciousness is called samādhi, or trance.
We should always try to mold the activities of our lives in such a way that we will constantly remember Viṣṇu, or Kṛṣṇa. That is Kṛṣṇa consciousness. Whether one concentrates his mind on the four-handed form of Viṣṇu or on the form of two-handed Kṛṣṇa, it is the same. The Padma Purāṇa recommends: somehow or other always think of Viṣṇu, without forgetting Him under any circumstances. Actually this is the most basic of all regulative principles. For, when there is an order from a superior about doing something, there is simultaneously a prohibition. When the order is that one should always remember Kṛṣṇa, the prohibition is that one should never forget Him. Within this simple order and prohibition, all regulative principles are found complete.
This regulative principle is applicable to all varṇas and āśramas, the castes and occupations of life. There are four varṇas, namely the brāhmaṇas (priests and intellectuals), the kṣatriyas (warriors and statesmen), the vaiśyas (businessmen and farmers) and the śūdras (laborers and servants). There are also four standard āśramas, namely brahmacarya (student life), gṛhastha (householder), vānaprastha (retired) and sannyāsa (renounced). The regulative principles are not only for the brahmacārīs (celibate students) to follow, but are applicable for all. It doesn't matter whether one is a beginner—a brahmacārī—or is very advanced—a sannyāsī. The principle of remembering the Supreme Personality of Godhead constantly and not forgetting Him at any moment is meant to be followed by everyone without fail.