Bhagavad Gita
Chapter 2 · Verse 48
योगस्थः कुरु कर्माणि सङ्गं त्यक्त्वा धनञ्जय। सिद्ध्यसिद्ध्योः समो भूत्वा समत्वं योग उच्यते॥
yoga-sthaḥ kuru karmāṇi saṅgaṁ tyaktvā dhanañjaya, siddhy-asiddhyoḥ samo bhūtvā samatvaṁ yoga ucyate
The Gita defines yoga here not as a posture but as balance of mind: the ability to give real effort without being thrown off by whether it succeeds or fails.
Do your work in balance. That steadiness of mind is the real practice.