Create Your Own Sankalpa with Patience and Authenticity

Arrival of the Sun, Kenojuak Ashevak, 1962, stonecut on paper
For far too long, at various yoga studios from a horde of different yoga teachers, I would hear the words “take this moment to set your intention.”
Firstly, they give you about ten seconds to whip something out of the void before they initiate a vigorous asana practice (unless, of course, you’re rocking Yin or Nidra classes).
And secondly, how do I properly create one within the yogic tradition?