“Srimad- Bhagavatam (2.3.10) advises:
akamah sarva-kamo va moksa-kama udara-dhih
tivrena bhakti-yogena yajeta purusam param
“Whether one is freed from all material desires, is full of material desires, or desires to become one with the Supreme, he should engage in devotional service.” In this way, not only will the devotee’s desires be fulfilled, but the day will come when he will have no other desire than to serve the lotus feet of the Lord. One who engages in the service of the Lord with some motive is called a sakama-bhakta, and one who serves the Lord without any motives is called an akama-bhakta. Krishna is so merciful that He turns a sakama-bhakta into an akama-bhakta. A pure devotee, an akama-bhakta, who has no material motives, is satisfied simply to serve the lotus feet of the Lord. This is confirmed in Bhagavad-gita (6.22). Yam labdhva caparam labham manyate nadhikam tatah: if one engages in the service of the lotus feet of the Lord, he does not want anything more. This is the highest stage of devotional service. The Lord is so kind even to a sakama-bhakta, a motivated devotee, that He satisfies his desires in such a way that one day he becomes an akama-bhakta. Dhruva Maharaja, for example, became a bhakta with the motive of getting a better kingdom than that of his father, but finally he became an akama-bhakta and said to the Lord, svamin krtartho’smi varam na yace: “My dear Lord, I am very satisfied simply to serve Your lotus feet. I do not want any material benefits.” Sometimes it is found that a small child eats dirty things, but his parents take away the dirty things and offer him a sandesa or some other sweetmeat. Devotees who aspire for material benedictions are compared to such children. The Lord is so kind that He takes away their material desires and gives them the highest benediction. Therefore, even for material motives, one should not worship anyone other than the Supreme Personality of Godhead; one must fully engage himself in the devotional service of the Lord so that all his desires will be fulfilled and at the end he can go back home, back to Godhead.
This is explained in Chaitanya-caritamrta (Madhya 22.37-39, 41) as follows. Anyakami–a devotee may desire something other than service to the lotus feet of the Lord; yadi kare krsnera bhajana–but if he engages in Lord Krishna’s service; na magiteha Krishna tare dena sva-carana—Krishna gives him shelter at His lotus feet, even though he does not aspire for it. Krishna kahe–the Lord says; ama bhaje–“He is engaged in My service”; mage visaya-sukha–“but he wants the benefits of material sense gratification.” Amrta chadi’ visa mage:–“such a devotee is like a person who asks for poison instead of nectar.” Ei bada murkha: “That is his foolishness.” Ami-vijna: “But I am experienced.” Ei murkhe ‘visaya’ kene diba: “Why should I give such a foolish person the dirty things of material enjoyment?” Sva-caranamrta: “It would be better for Me to give him shelter at My lotus feet.” ‘Visaya’ bhulaiba: “I shall cause him to forget all material desires.” Kama lagi’ Krishna bhaje–if one engages in the service of the Lord for sense gratification; paya Krishna-rase–the result is that he ultimately gets a taste for serving the lotus feet of the Lord. Kama chadi’ ‘da’ haite haya abhilase: He then gives up all material desires and wants to become an eternal servant of the Lord.”
A.C. Bhaktivedanta Swami Prabhupada (2014 edition), “Srimad Bhagavatam”, Fifth Canto, Chapter 19 – Text 27