Your right is to action alone;
Never to its fruits at any time.
Never should the fruits of action be your motive;
Never let there be attachment to inaction in you.
Fixed in yoga, perform actions,
Having abandoned attachment, Arjuna,
And having become indifferent to success or failure.
It is said that evenness of mind is yoga.
कर्मण्येवाधिकारस्ते
मा फलेषु कदाचन ।
मा कर्मफलहेतुर् भूर्
मा ते सङ्गो ऽस्त्व् अकर्मणि ॥
योगस्थः कुरु कर्माणि
सङ्गं त्यक्त्वा धनंजय ।
सिद्ध्यसिद्ध्योः समो भूत्वा
समत्वं योग उच्यते ॥
From the Bhagavad Gītā, book II, verses 47–48. Translation by Winthrop Sargeant. Yoga here refers to "discipline, steadfastness."