It is very difficult to convince those who adhere to fruitive activities that they should render devotional service to Lord Kṛṣṇa. The reason is that most fruitive workers are foolish, fallen and impious. Therefore all their activities are whimsical and motivated by evil. Their intelligence and expertise are thus utilized in defiance of the Supreme Lord. They are totally in the grip of the illusory potency, māyā, and so they imagine themselves to be the Supreme Lord Himself, or at least His biggest competitor, like the demon Śiṣupāla. They simply try to enjoy this material world in various ways. In fact, their hopes for enjoying this world are just make—believe, or māyā, and this make-believe yearning leaves them hopelessly cheated. Yet they cannot give up the hope to enjoy. And when they realize that fruitive activities are futile and are more or less forced to renounce them, then such renunciation becomes merely another illusory scheme for a greater enjoyment.
Those who hanker after the fruits of their actions undertake many hardships in executing their work, their imagination wanders like an untethered bull, and all the while their mind dictates to them that they are the actual enjoyers. Therefore, without disrupting the minds of these foolish, perverted karmīs, the intelligent person should engage them in doing what they are expert in and using the fruits in Lord Kṛṣṇa's service. Such a course of action will automatically uncover the fruitive workers' eternal relationship with Lord Kṛṣṇa. So, to instruct the people for their benefit, the servant of Kṛṣṇa, who is free from the reactions of fruitive activities, will lead a life seemingly like that of the fruitive workers, but actually he is all along performing karma-yoga.
Had not Lord Kṛṣṇa mercifully instructed the process of karma-yoga to His devotee Śrī Arjuna, the ignorant souls would have suffered miserably for all time. These wretched karmīs have the noose of māyā constantly wrapped around their necks and are living from one distress to another, but because the Lord's deluding potency covers their intelligence, they cannot understand any of this. However much they might pretend to be the controllers, they are being continuously goaded by māyā, who leaves them helpless and impotent. Lord Kṛṣṇa has explained this in the Bhagavad-gītā (3.27), "The spirit soul bewildered by the influence of false ego thinks himself the doer of activities that are in actuality carried out by the three modes of material nature."