Āsana, being the initial limb of Haṭha, is spoken of first.
Āsana brings about steadiness, improved health and lightness of limb.
“For me, still to this day, one of the simplest, direct and most succinct definitions on the purpose of Āsana within the processes and practices of Haṭha Yoga, is the definition offered in the Haṭha Pradīpikā Chapter One verse 17.
It is a definition valid for any situation, discussion or presentation, or as a response to questions from any background, or level of interest around why we practice Āsana.
It can also be a springboard to linking physiological qualities, such as the relationship of Agni, to the energetic qualities of health and lightness of limb. Or investigation of the commentary by Brahmānada, as that explores psychological qualities such as the relationship of the Guṇa, Rajas, to mental qualities such as steadiness.”