Here are 10 timeless powerhouse lines that capture the rebel-spirit and soul-science of yoga.  Read them, breathe them, live them:

1. “योगः चित्त-वृत्ति निरोधः | Yogas chitta-vṛtti nirodhaḥ
   Yoga is the stilling of the mind’s whirlwinds.  — Patañjali, Yoga Sūtra 1.2   
2. “Be steadfast in yoga, O Arjuna—do your duty, drop the outcome.  Even-mindedness is yoga.” — Bhagavad Gītā 2.48   
3. “Yoga is skill in action.” — Bhagavad Gītā 2.50   
4. “When the five senses and the mind are still, and reason rests in silence, the highest path begins.” — Katha Upaniṣad 2.3.10   
5. “Arise! Awake! Stop not till the goal is reached.” — Katha Upaniṣad 1.3.14 (popularized by Swami Vivekananda)   
6. “अभ्यासवैराग्याभ्यां तन्निरोधः | Abhyāsa-vairāgyābhyāṁ tan nirodhaḥ
   Practice + non-attachment = mastery of the mind. — Yoga Sūtra 1.12   
7. “Prayatna śaithilya ananta samāpattibhyām.”
   Perfection in posture comes when effort melts into infinity. — Yoga Sūtra 2.47   
8. “Yoga teaches us to cure what need not be endured—and to endure what cannot be cured.” — B. K. S. Iyengar   
9. “Do your practice, and all is coming.” — K. Pattabhi Jois   
10. “Inhale, and God approaches you… Exhale, and you approach God.” — T. Krishnamacharya   

Pin these to your mental vision-board, recite them between reps or breaths, and let their ancient fire rocket-boost your modern practice!