SB 5.19.14

yathaihikāmuṣmika-kāma-lampaṭaḥ
 suteṣu dāreṣu dhaneṣu cintayan
śaṅketa vidvān kukalevarātyayād
 yas tasya yatnaḥ śrama eva kevalam
Word for word: 
yathā — as; aihika — in the present life; amuṣmika — in the expected future life; kāma-lampaṭaḥ — a person who is very attached to lusty desires for bodily enjoyment; suteṣu — children; dāreṣu — wife; dhaneṣu — wealth; cintayan — thinking about; śaṅketa — is afraid; vidvān — a person advanced in spiritual knowledge; ku-kalevara — of this body, which is full of stool and urine; atyayāt — because of loss; yaḥ — anyone; tasya — his; yatnaḥ — endeavors; śramaḥ — a waste of time and energy; eva — certainly; kevalam — only.
Translation: 
Materialists are generally very attached to their present bodily comforts and to the bodily comforts they expect in the future. Therefore they are always absorbed in thoughts of their wives, children and wealth and are afraid of giving up their bodies, which are full of stool and urine. If a person engaged in Kṛṣṇa consciousness, however, is also afraid of giving up his body, what is the use of his having labored to study the śāstras? It was simply a waste of time.
Purport: 

At the time of death a materialist thinks of his wife and children. He is absorbed in thinking of how they will live and who will take care of them after he leaves. Consequently he is never prepared to give up his body; rather, he wants to continue to live in his body to serve his society, family, friends and so on. Therefore by practicing the mystic yoga system one must become detached from bodily relationships. If despite practicing bhakti-yoga and studying all the Vedic literature, one is afraid of giving up his bad body, which is the cause of all his suffering, what is the use of his attempts to advance in spiritual life? The secret of success in practicing yoga is to become free from bodily attachments. Śrīla Narottama dāsa Ṭhākura says, deha-smṛti nāhi yāra, saṁsāra-bandhana kāhāṅ tāra: one whose practice has freed him from the anxieties of bodily needs is no longer in conditional life. Such a person is freed from conditional bondage. A person in Kṛṣṇa consciousness must fully discharge his devotional duties without material attachment. Then his liberation is guaranteed.