Devoted to his own respective action (karma), a man attains perfection (saṃsiddhi). How one devoted to his own action finds perfection (siddhi), hear that.
Each one achieves success by focusing on his own action; hear how one finds success by focusing on his own action.
(45) By [doing] the work that is proper to him [and] rejoicing [in the doing], a man succeeds, perfects himself. [Now] hear just how a man perfects himself by [doing and] rejoicing in his proper work.
18.45 Being devoted to his own duty, man attains complete success. Hear that as to how one devoted to his own duty achieves success.
18.45 Devoted to his duty, man attains perfection. Hear now how one devoted to his own duty attains perfection.
18.45 Each man devoted to his own duty attains perfection. How he attains perfection while being engaged in his own duty, hear now.