Yoga is a set of tools and techniques (a small number of which are physical exercises) designed to purify the body, maintain health, enable the mind to be calm, allow energy to move and facilitate a meditation practice. In the process we grow, learn about ourselves, work at the edge of our capabilities (which is very often much further than we believe), and as a by-product we may experience an increase in muscle fascia flexibility.
To obsess about flexibility seems a bit silly in that context. In Ashtanga yoga, for example, there are a progression of 6 sequences that allow stronger and more flexible people to continually be challenged and work at the edge of their ability, but if someone only ever works on the Primary Series or modifies their practice to their limitations, are they not doing yoga, progressing, learning? Of course they are! Patanjali’s Yoga Sutras (a seminal work in the field) has only 3 of 195 verses that mention postures, and he tells us that they should be comfortable and relaxed. He also tells us that a “successful” practice is one that is done regularly over a period of time and without attachment to the outcome. In many ways, yoga has become bastardised by a fixation on physical outcome.
Yoga was designed as a spiritual practice with a physical element to it, but has become a physical practice with a spiritual element to it. This grossly understates its potential. Genetics define capability – everyone’s edge is different, and competition (like running for example), is merely an exploration of relative genetics. For the majority, it’s about our own limits. Yoga is not about doing posture X – it’s about trying to do it, changing physiologically as you try, learning from it, making the impossible possible and defining a new limit.