Journey and Destination

There are very many ways to define the meaning of “yoga”
Patañjali begins the Yoga Sutras with what we can call a “classical definition” of yoga

What is Yoga?

YS 1:2

“Yoga is the settling of the mind into silence”
Alistair Shearer

“Complete mastery over the roaming tendencies of the mind is yoga”
Pandit Rajmani Tigunait

“The restraint of the modifications of the mind-stuff is yoga”
Swami Satchitananda

“Yoga is the containment of movement in the psyche”
Paul Harvey

So we can see that yoga is a mental process and a mental state
It is a process whereby the mind progressively comes to a clear/calm/contained/tamed/mastered state

And yoga is that state of clear/calm/contained/tamed/mastered mind

Yoga is both journey and destination

… and then …

YS 1:3

“When the mind is settled, we are established in our essential nature, which is unbounded consciousness."
Alistair Shearer

“Then the Seer [Self] becomes established in its essential nature."
Pandit Rajmani Tigunait

“Then the Seer [Self] abides in his own nature."
Swami Satchitananda

“Then the Seer’s own character remains."
Paul Harvey

We reflect our True Self, our True Nature, our Deepest Reality, and It is fully and completely present and established in our human life, shining without block or hindrance
One of the names Patañjali gives this Truth is the “Seer”

Note that there is no mention of the physical postures, or any other specific techniques
The equating of the word “yoga” with bending and stretching is a very modern phenomenon
Patañjali goes on to offer a very broad spectrum of possible processes, principles and practices that can constitute the journey, and to define the destination and its results

If we are not working to quieten/calm/master the mind in order to progress spiritually we are not, in the classical sense of the word, practising yoga

References;

yogaḥ citta-vṛtti-nirodhaḥ
Yoga sutras 01:02

tadā draṣṭuḥ svarūpe-avasthānam
Yoga sutras 01:03