Here are a few definitions of the meaning of Yoga taken from the ancient spiritual books.
1. According to the Yoga Sutras —
"योगश्चित्तवृत्तिनिरोधः’’* Yogah chitta vritti nilodhah.(1/2)
Yoga is the removal of the fluctuations of the mind.
2. According to the Bhagwad Gita——
*‘‘योगः कर्मसु कौशलम्’’*yogah karmasu kaushalam (2/50)
Yoga is excellence at work.
"समत्वं योग उच्यते’’* (गीता 2/48) Samatvam yoga uchyate.
Evenness of mind called is yoga.
"दुःख संयोगवियोगं योग संज्ञितम्’’* (6/23) Dukha sanyoga viyogam yoga samjnitam.
When the mind is free from all pain producing factors, that pain free state of the mind is called yoga.
3. According to the Mahopanishad—
*‘‘मनः प्रशमनोपायो योग इत्यभिधीयते’’*5/42) Manah prashamano- payo yoga ityabhidhiyate
Yoga is the system of preparing a healthy mind.
4. According to sage Yajnavalkya—
*‘‘संयोग योगयुक्तो इति युक्तो जीवात्मा परमात्मनो।’’* Sanyoga yoga yukto iti yukto jivatma parmatmano.
Yoga is connection between human beings and God.
5. According to the Kaivalya Upanishad—
*‘‘श्रद्धा भक्ति ध्यान योगादवेहि’’ Shraddha Bhakti dhyana yogadavehi.
Yoga is knowledge of the Soul through trust, devotion and meditation.
6. According to Vishnu Purana —
*‘‘योगः संयोग इत्यक्तः जीवात्मा परमात्मनो।’’* Yogah sanyogah ityaktah jevatma parmatmano.
Yoga is Union between God and humankind.
7--According to the Maitrayani Upanishada—
Yoga is the name of that state where mind, the physical body and consciousness become one.
8-According to kathopa Upanishada—
Yoga is a state of harmony achieved by the mind and physical body through awareness.
9- According to Agni purana——
Yoga is a deep dedication to God.
10- According to Kevalam Raja yogaya
Yoga means to be the controller of one's mind, to become the king of one's mind.
Try to remember and apply these 5 rules in life--/
1-----try your best to keep Cool and calm in difficulties, adversities and trying condition of life.
2----forget not the goal. Everyday place a step further towards the goal.
3----apply yourself diligently to yoga.
4---expand, evolve, have a larger heart, mix with all. Be humble.
5---lead a simple life, let your thought be lofty.