Whatever your natural work — pursue it with your whole heart, and perfection will follow. That is the essence of this shloka. Krishna tells Arjuna: a person joyfully devoted to their own duty attains complete perfection. Now hear how.
The word 'abhiratah' is important. It does not mean merely performing a duty out of obligation. It means being joyfully absorbed in it — the way a potter loses track of time at the wheel, the way a gardener forgets the world while tending to plants. That quality of absorbed delight in one's own work is the secret ingredient.
This is one of the most practical teachings in the entire Gita. Perfection does not require renouncing the world or switching to someone else's path. It requires only this: do your own thing, fully and gladly. The rest follows.