SB 11.10.31

guṇāḥ sṛjanti karmāṇi
 guṇo ’nusṛjate guṇān
jīvas tu guṇa-saṁyukto
 bhuṅkte karma-phalāny asau
Synonyms: 
guṇāḥ — the material senses; sṛjanti — create; karmāṇi — pious and impious material activities; guṇaḥ — the three modes of nature; anusṛjate — set into motion; guṇān — the material senses; jīvaḥ — the minute living entity; tu — indeed; guṇa — the material senses or the material modes of nature; saṁyuktaḥ — fully engaged in; bhuṅkte — experiences; karma — of activities; phalāni — the various results; asau — the spirit soul.
Translation: 
The material senses create material activities, either pious or sinful, and the modes of nature set the material senses into motion. The living entity, being fully engaged by the material senses and modes of nature, experiences the various results of fruitive work.
Purport: 

It has been explained in the previous verses that the living entity under the control of fruitive activities is pushed down into a hellish condition of life. In this verse the exact nature of the living entity’s dependence on fruitive activities is described. One can observe that one’s activities are performed by the material senses and that the living entity himself is merely conscious of such activities. One may be worshiping the demigods, enjoying sex or performing agricultural or intellectual activities, but in all cases the material senses are performing the work.

One may argue that the spirit soul initiates the activities of the senses and thus is the ultimate doer, but such false egotism is negated in this verse by the statement guṇāḥ sṛjanti karmāṇi guṇo ’nusṛjate guṇān. The three modes of nature — goodness, passion and ignorance — stimulate the functions of the material senses, and the living entity, coming under the control of a particular mode of nature, merely experiences the good and bad results of his work. This does not negate the concept of free will, since the living entity chooses to associate with different modes of nature. By one’s eating, speaking, sexual activities, occupation, etc., one associates with various modes of nature and acquires a particular mentality. But in all cases the modes of nature themselves are acting, not the living entity. The word asau in this verse indicates that the living entity falsely considers himself to be the performer of work carried out by nature. As stated in Bhagavad-gītā (3.27):

prakṛteḥ kriyamāṇāni
 guṇaiḥ karmāṇi sarvaśaḥ
ahaṅkāra-vimūḍhātmā
 kartāham iti manyate

“The bewildered spirit soul, under the influence of the three modes of material nature, thinks himself to be the doer of activities, which are in actuality carried out by nature.” The conditioned soul can be liberated simply by giving up this false egoistic conception of life and taking to the devotional service of the Lord, by which the living entity, or marginal potency of the Supreme Personality of Godhead, escapes the disturbing influence of the external potency called māyā. In the devotional service of the Lord the liberated entity realizes his actual form of eternity, knowledge and bliss.

It is natural to perform activities with a desire to achieve a good result. The best results, however, can be attained by one who engages in the devotional service of the Lord with a desire to be reinstated in his constitutional position as the Lord’s loving servant. In this way the tendency to exploit one’s own activities for a particular result can be purified; then the modes of nature and the material senses will no longer engage the living entity in illusion. The living entity is by nature blissful, and when his illusion ceases, all suffering comes to an end. The liberated soul is then fit to reside in Vaikuṇṭha, the kingdom of God.