yogashchittavrttinirodhah
Yoga is the ability to direct the mind exclusively toward an object and sustain that direction without distraction.
Patanjali's Yoga Sutra 1:2
Karmanyevadhikaraste ma phalesu kadacana
ma karmaphalaheturbhurma te sango stvakarmani
To action alone thou has the right, never to the fruits thereof. Let not the fruit of action be thy motive, nor let thy attachment be to inaction.
Bhagavad Gita 2:47
yogasthah kuru karmani sangam tyaktva dhananjaya
siddhyaasiddhyoh samo bhutva samatvam yoga ucyate
Steadfast in yoga do thy actions, free from selfish desires, being the same in success or failure. Yoga is evenness of mind.
Bhagavad Gita 2:48
99% practise, 1% theory
Pattabhi Jois