Bhagavad Gita, Chapter 6, Verse 14

With the heart serene and fearless, firm in the vow of a Brahmachâri, with the mind controlled, and ever thinking of Me, let him sit in Yoga having Me as his supreme goal.

The posture and setup were never the actual point, they were always in service of one single, clear focus.

This pulls the practical instructions from the last few verses toward their real purpose. Every physical detail described so far exists to support this one thing, a mind steady enough to hold a single, undivided focus.