Shree Krishna states in this verse that we should perform auspicious and service such acts of sacrifice, charity and penance with the attitude of selflessness and with the devotion to the Supreme Lord. If we cannot do with consciousness, we should at least do it without the desire for reward.
एतान्यपि तु कर्माणि सङ्गं त्यक्त्वा फलानि च |
कर्तव्यानीति मे पार्थ निश्चितं मतमुत्तमम् || 6||
These activities must be performed without attachment and expectation for rewards. This is my definite and supreme verdict, O Arjun.
A mother feeds her baby with her milk and nourishes her baby fulfilling her motherhood. Similarly a cow grazes in sun whole day to feed milk to her calf. A cow does that duty selflessly. All these activities are sacred as they are done without the desire to get reward.
In other words, all sacrifices, charity and penance meant for material advancement in life should be given up. Sacrifices should be done to purify and elevate us to the spiritual plane.