Practicing yoga with strength and in a relaxed manner gives rise to harmony with the physical body (asana).
Patanjali describes asana only once in the yoga sutras. He doesn't talk about alignment, loose hamstrings, or deep backbends. Sutra 2.46 simply says, "Sthira Sukham Asanam."
To put it simply: yoga asana is a balance between effort and ease. The postures should teach us how to make wise choices, that will help us to move toward homeostasis. We will often find that balance requires us to move toward the opposite of our usual habits and comfort zones. For many of us, this means learning how to YIELD.
So the question for many of us becomes: how can we incorporate more ease (sukham) into our practice? Both on and off the mat, we're often used to pushing toward “success”, multitasking, or perfecting. Instead, how about moving toward refining, and quieting from the inside out? Finding sukham takes LESS effort... but requires more awareness.