1 Gita Sloka Every Day - Chapter 18 - Moksha Sanyasa Yoga - Sloka 45

The entire content of this mail is from Shri V N Gopala Desikan's  Srimad Bhagavad Gita, published by Vishishtadvaita Research Centre, Chennai and The Bhagavad Gita by Swami Chidbhavananda published by Ramakrishna Mission

The ways and means of liberation are now expounded

The Four Fold Caste System Explained 41-48

1 Gita Sloka  Every Day - Chapter 18 - Moksha Sanyasa Yoga - Sloka 45

Sve sve karmani abhiratah sam siddhim labhate narah I

Sva karma niratah yatha vindati tat shrunu II sloka 45

स्वे स्वे कर्मणि अभिरतः सं सिद्धिं लभते नरः I 

स्व कर्म निरतः यथा विन्दति तत् शृणु II श्लोक 45

Devoted each to his own duty, man attains the highest perfection. How engaged in his own duty, he attains this perfection, do hear.

To whatever station in life man has made himself competent, that is verily his svadharma. He who discharges his svadharma jubilantly and efficiently turns out to be a good sadhaka. The temporary disgust that Arjuna harboured for his svadharma was not born of a mature understanding. It was the oitcome of a momentary delusion. He who abhors his duty can never become great. A model student is he who applies himself diligently and delightfully to his studies. HE is loyal to the class in which he is placed, so that he may step over into  higher class when the time for it comes. It is his svadharma to go steadily into teh higher classes. This principle, however does not apply to one's position in life. If a scavenger thinks of changing his occupation for a better one, he may thereby prove himself worldly wise. But that attitude is definitely a hindrance to his spiritual growth. Through his seemingly humble svadharma he can rise to be a perfect yogi. For. no work is ugly or less for a sadhaka. Any and every becomes worship when the attitude is sound. 

The how of it is explained in the next sloka.