(Click to enlarge painting of Krishna, the Supreme Personality of Godhead)
By worship of the Lord, who is the source of all beings and who is all-pervading, man can, in the performance of his own duty, attain perfection.
As stated in the Fifteenth Chapter, all living beings are fragmental parts and parcels of the Supreme Lord. As such, the Supreme Lord is the beginning of all living entities. This is confirmed in the Vedānta-sūtra—janmādy asya yataḥ. The Supreme Lord is therefore the beginning of life of every living entity. And the Supreme Lord, by His two energies, His external energy and internal energy, is all-pervading. Therefore one should worship the Supreme Lord with His energies. Generally the Vaiṣṇava devotees worship the Supreme Lord with His internal energy. His external energy is a perverted reflection of the internal energy. The external energy is a background, but the Supreme Lord by the expansion of His plenary portion as Paramātmā is situated everywhere. He is the Supersoul of all demigods, all human beings, all animals, everywhere. One should therefore know that as part and parcel of the Supreme Lord it is his duty to render service unto the Supreme. Everyone should be engaged in devotional service to the Lord in full Kṛṣṇa consciousness. That is recommended in this verse.
Everyone should think that he is engaged in a particular type of occupation by Hṛṣīkeśa, the master of the senses. And by the result of the work in which one is engaged, the Supreme Personality of Godhead, Śrī Kṛṣṇa, should be worshiped. If one thinks always in this way, in full Kṛṣṇa consciousness, then, by the grace of the Lord, he becomes fully aware of everything. That is the perfection of life. The Lord says in Bhagavad-gītā (12.7), teṣām ahaṁ samuddhartā. The Supreme Lord Himself takes charge of delivering such a devotee. That is the highest perfection of life. In whatever occupation one may be engaged, if he serves the Supreme Lord he will achieve the highest perfection.
(Bhagavad-gītā As It Is 18.46, Translation and Purport)