SB 3.31.31

tad-arthaṁ kurute karma
 yad-baddho yāti saṁsṛtim
yo ’nuyāti dadat kleśam
 avidyā-karma-bandhanaḥ
Synonyms: 
tat-artham — for the sake of the body; kurute — he performs; karma — actions; yat-baddhaḥ — bound by which; yāti — he goes; saṁsṛtim — to repeated birth and death; yaḥ — which body; anuyāti — follows; dadat — giving; kleśam — misery; avidyā — by ignorance; karma — by fruitive activities; bandhanaḥ — the cause of bondage.
Translation: 
For the sake of the body, which is a source of constant trouble to him and which follows him because he is bound by ties of ignorance and fruitive activities, he performs various actions which cause him to be subjected to repeated birth and death.
Purport: 

In Bhagavad-gītā it is said that one has to work to satisfy Yajña, or Viṣṇu, for any work done without the purpose of satisfying the Supreme Personality of Godhead is a cause of bondage. In the conditioned state a living entity, accepting his body as himself, forgets his eternal relationship with the Supreme Personality of Godhead and acts on the interest of his body. He takes the body as himself, his bodily expansions as his kinsmen, and the land from which his body is born as worshipable. In this way he performs all sorts of misconceived activities, which lead to his perpetual bondage in repetition of birth and death in various species.

In modern civilization, the so-called social, national and government leaders mislead people more and more, under the bodily conception of life, with the result that all the leaders, with their followers, are gliding down to hellish conditions birth after birth. An example is given in Śrīmad-Bhāgavatam. Andhā yathāndhair upanīyamānāḥ: when a blind man leads several other blind men, the result is that all of them fall down in a ditch. This is actually happening. There are many leaders to lead the ignorant public, but because every one of them is bewildered by the bodily conception of life, there is no peace and prosperity in human society. So-called yogīs who perform various bodily feats are also in the same category as such ignorant people because the haṭha-yoga system is especially recommended for persons who are grossly implicated in the bodily conception. The conclusion is that as long as one is fixed in the bodily conception, he has to suffer birth and death.