“In this Sūtra,
Patañjali lists the nine kinds of obstacles
that are confronted by those who,
though fit and able to meditate on Īśvara,
neglect to do so.”
– T Krishnamacharya on Yoga Sūtra Chapter One verse 30

“As Prāṇāyāma dissolves the covering of the light,
fitness of the mind for concentration arises.”
– Paul Harvey on  Yoga Sūtra Chapter Two verse 52

“A person who is physically fit and
who has been cleansed by the Agni of Dhyānam
has no fear of sickness, disease, age or death.”
– T Krishnamacharya on Yoga Sūtra Chapter Three verse 2

“Even if you only do postures
and practise breath control,
with no meditation,
there is still a mental effect.”
– From interviews with T Krishnamacharya by Sarah Dars,
published in Viniyoga Review no 24, December 1989

“Āsana and Prāṇāyāma can, according to the Yoga Sūtra,
create a condition where the mind is fit for Dhāraṇā.”
– TKV Desikachar Religiousness in Yoga Chapter Eleven Page 156

“The role of Prāṇāyāma, both short-term and long-term,
is a vital consideration, integral to the essence of Dhyāna,
in the preparation by honing the mind’s fitness for Dharana.
Both within the teachings of Patañjali and, especially as seen
within the Yoga taught by Krishnamacharya and Desikachar.”
– 108 Prāṇāyāma Practice Pointers

“Prāṇāyāma is regarded as a Tapas,
a Kriyā, which cleanses the Nāḍī,
It is a Sādhana which sharpens Agni
and helps to dissolve obstacles, thus
making the mind fit for attention.”
– 108 Yoga Practice Pointers

“The principles of Cikitsā, Rakṣaṇa and Śikṣaṇa Krama
are more applicable to the ‘mindset’ of a person,
rather than looking through the ‘fitness’ of their body.”
– 108 Teaching Path Pointers