Jitāsano jita-śvāso jita-saṅgo jitendriyaḥ
Sthūle bhagavato rūpe manaḥ sandhārayed dhiyā
Perfection in sitting posture should be achieved through persistent practice. In other words, the aspirant should be able to sit in the same posture for any length of time. This is the first step.
from Srimad Bhagavatam – Day 67(Translations of Pujya Sri Ganapathy Sachchidananda Swamiji’s daily explanation of Srimad Bhagavatam on ETV from December 2015 onwards are compiled by Parimala Eshwarla)