Bg 6.11-12

sucau dese pratisthapya
sthiram asanam atmanah
naty-ucchritam nati-nicam
cailajina-kusottaram

tatraikagram manah krtva
yata-cittendriya-kriyah
upavisyasane yunjyad
yogam atma-visuddhaye

Word for word: 
sucau — in a sanctified; dese — land; pratisthapya — placing; sthiram — firm; asanam — seat; atmanah — his own; na — not; ati — too; ucchritam — high; na — nor; ati — too; nicam — low; caila-ajina — of soft cloth and deerskin; kusa — and kusa grass; uttaram — covering; tatra — thereupon; eka-agram — with one attention; manah — mind; krtva — making; yata-citta — controlling the mind; indriya — senses; kriyah — and activities; upavisya — sitting; asane — on the seat; yunjyat — should execute; yogam — yoga practice; atma — the heart; visuddhaye — for clarifying.

Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
To practice yoga, one should go to a secluded place and should lay kusa grass on the ground and then cover it with a deerskin and a soft cloth. The seat should be neither too high nor too low and should be situated in a sacred place. The yogi should then sit on it very firmly and practice yoga to purify the heart by controlling his mind, senses and activities and fixing the mind on one point.

Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
“Sacred place” refers to places of pilgrimage. In India the yogis – the transcendentalists or the devotees – all leave home and reside in sacred places such as Prayaga, Mathura, Vrndavana, Hrsikesa and Hardwar and in solitude practice yoga where the sacred rivers like the Yamuna and the Ganges flow. But often this is not possible, especially for Westerners. The so-called yoga societies in big cities may be successful in earning material benefit, but they are not at all suitable for the actual practice of yoga. One who is not self-controlled and whose mind is not undisturbed cannot practice meditation. Therefore, in the Brhan-naradiya Purana it is said that in Kali-yuga (the present yuga, or age), when people in general are short-lived, slow in spiritual realization and always disturbed by various anxieties, the best means of spiritual realization is chanting the holy name of the Lord.

harer nama harer nama
harer namaiva kevalam
kalau nasty eva nasty eva
nasty eva gatir anyatha

“In this age of quarrel and hypocrisy the only means of deliverance is chanting the holy name of the Lord. There is no other way. There is no other way. There is no other way.”