Be Steadfast in Yoga

karmaṇy evādhikāras te mā phaleṣu kadācana
mā karma-phala-hetur bhūr mā te saṅgo 'stv akarmaṇi

yoga-sthaḥ kuru karmani sanyugam tyaktvā dhananjaya
siddhy-asiddhyoḥ samo bhutvā samatvam yoga ucyate

कर्मण्य् एवाधिकारस् ते मा फलेषु कदाचन
मा कर्मफलहेतुर् भूर् मा ते सङ्गो ऽस्त्व् अकर्मणि
योगस्थः कुरु कर्मनि सन्युगम् त्यक्त्वा धनन्जय
सिद्ध्यसिद्ध्योः समो भुत्वा समत्वम् योग उच्यते

"Your right is to work only, but never with its fruits; let not the fruits of action be your motive, nor let your attachment be to inaction.  Perform action, O Arjuna, being steadfast in Yoga, abandoning attachment and balanced in success and failure.  Evenness of mind is called Yoga."
~2.47-48 Bhagavad Gītā