Link to purport by A C Bhaktivedanta Swami Srila Prabhupada

Transcript of Bhakti-Shastri class on this verse by Chaitanya Charan

So He describes the process in the next verse, 

Bg 18.46

yataḥ pravṛttir bhūtānāṁ
yena sarvam idaṁ tatam
sva-karmaṇā tam abhyarcya
siddhiṁ vindati mānavaḥ

Synonyms: 

yataḥ — from whom; pravṛttiḥ — the emanation; bhūtānām — of all living entities; yena — by whom; sarvam — all; idam — this; tatam — is pervaded; sva–karmaṇā — by his own duties; tam — Him; abhyarcya — by worshiping; siddhim — perfection; vindati — achieves; mānavaḥ — a man.

Translation: 

By worship of the Lord, who is the source of all beings and who is all-pervading, a man can attain perfection through performing his own work.

siddhiṁ vindati mānavaḥ, one can attain perfection.

The key word here is sva-karmaṇā tam abhyarcya, whatever work one is doing sva-karmaṇā, tam abhyarcya, worship that Supreme being, 

BG never says Karma He Puja Hai what BG is saying here is By Your Work Worship Him, by devotion to the Supreme Lord translate work into worship, we develop a spiritual consciousness in worshiping Supreme Lord and we carry that consciousness in our work and that is how we become spiritualized. Tama, who is tama here, Krishna is not come to the level of Bhakti Yoga in this section so He is talking as third person, so here He is describing as that Supreme Lord and He is describing the characteristic of that Supreme Lord, 

yataḥ pravṛttir bhūtānāṁ, from whom all living beings come, pravrtti can mean all living being and all of existence, Sri Krishna has talked about He being source of all existence several times especially in 10.8 where He said Aham Servasya Pravabho, everything comes from Me, 

yataḥ pravṛttir bhūtānāṁ
yena sarvam idaṁ tatam

so that Lord is not only source of everything but He pervades everything, that Supreme Being exists in all creation, sva-karmaṇā tam abhyarcya, He is source and He is sustainer, siddhiṁ vindati mānavaḥ, in this way one can attain perfection, 

Srila Prabhupada’s purport: Everyone should think that he is engaged in a particular type of occupation by Hṛṣīkeśa, the master of the senses.

End of transcription.