Spiritual service of the Lord has neither satiation nor end. One can go on increasing his hankerings for the loving transcendental service of the Lord, and yet he will not find satiation or end. By intense service of the Lord, one can experience the presence of the Lord transcendentally. Therefore seeing the Lord means being engaged in His service because His service and His person are identical. The sincere devotee should go on with sincere service of the Lord. The Lord will give proper direction as to how and where it has to be done.
(Srimad Bhagavatam----1:6:22----purport).

Transcendental service to the Lord is not mundane. The service attitude of the devotee gradually increases and never becomes slackened. Generally, in old age a person is allowed retirement from mundane service. But in the transcendental service of the Lord there is no retirement at all; on the contrary, the service attitude increases more and more with the progress of age. In the transcendental service there is no satiation, and therefore there is no retirement. Materially, when a man becomes tired by rendering service in his physical body, he is allowed retirement, but in the transcendental service there is no feeling of fatigue because it is spiritual service and is not on the bodily plane. Service on the bodily plane dwindles as the body grows older, but the spirit is never old, and therefore on the spiritual plane the service is never tiresome.
(Srimad Bhagavatam----3:2:3----purport).

When one engages in devotional service to the Lord in the nine different kinds of bhakti-yoga, as enunciated in authoritative scriptures, such as hearing (śravaṇam), chanting (kīrtanam), remembering, offering worship, praying and offering personal service—either in one of them, or two or three or all of them—he naturally has no opportunity to engage in the service of the three modes of material nature. Unless one has good engagements in spiritual service, it is not possible to get out of the attachment to material service. Those who are not devotees, therefore, are interested in so-called humanitarian or philanthropic work, such as opening a hospital or charitable institution. These are undoubtedly good works in the sense that they are pious activities, and their result is that the performer may get some opportunities for sense gratification, either in this life or in the next. Devotional service, however, is beyond the boundary of sense gratification.
(Srimad Bhagavatam----3:25:27----purport).

"O son of Mahārāja Nanda (Kṛṣṇa), I am Your eternal servitor, yet somehow or other I have fallen into the ocean of birth and death. Please pick me up from this ocean of death and place me as one of the atoms at Your lotus feet." Being pleased with the devotee, the Lord turns all his material impediments into spiritual service. In this connection Śrīla Viśvanātha Cakravartī Ṭhākura quotes a verse from the Viṣṇu Purāṇa:
hlādinī sandhinī samvit
tvayy ekā sarva-saṁsthitau
hlāda-tāpa-karī miśrā
tvayi no guṇa-varjite
In the material world, the spiritual energy of the Supreme Personality of Godhead is manifested as tāpa-karī, which means "causing miseries." Everyone hankers for happiness, but although happiness originally comes from the pleasure potency of the Supreme Personality of Godhead, in the material world, because of material activities, the pleasure potency of the Lord becomes a source of miseries (hlāda-tāpa-karī).
(Srimad Bhagavatam----6:4:27-28----purport).

Śrīla Bhaktisiddhānta Sarasvatī Ṭhākura remarks that people who are under the bodily conception of life are called materialists. If we accept the offerings of such people, place them before the Lord and invite Vaiṣṇavas to partake of the prasādam, that attempt will gain us only a material reputation, not the actual benefit of service to a pure Vaiṣṇava. One should therefore try to serve the Supreme Personality of Godhead by fully surrendering at His lotus feet. If one engages for the service of the Lord whatever money one has honestly earned, that is spiritual service to the Supreme Personality of Godhead, the spiritual master and the Vaiṣṇavas.
(Sri Caitanya Caritamrta----3:6:275----purport).

As we have learned from previous mantras, the brahmajyoti emanating from the transcendental body of the Lord is full of spiritual sparks that are individual entities with the full sense of existence. Sometimes these living entities want to enjoy their senses, and therefore they are placed in the material world to become false lords under the dictation of the senses. The desire for lordship is the material disease of the living being, for under the spell of sense enjoyment he transmigrates through the various bodies manifested in the material world. Becoming one with the brahmajyoti does not represent mature knowledge. Only by surrendering unto the Lord completely and developing one's sense of spiritual servicedoes one reach the highest perfectional stage.
(Sri Ishopanishad).