Like a blind person crossing a new space -
bring your mind's eye into the body
and feel your Way Around…
To me one of the first steps in yoga is to feel and connect with our bodies. There is no doubt "stretching and keeping elasticity" is a part of yoga, but asanas are so much more than that. We really begin to learn about asanas when we can deepen our experience with the body, and I believe one of the first steps that helps with that is just connecting with the body and feeling. Step away from the thoughts for a moment, do not judge, and just feel. While it is quite simple in theory, we find, as we move into a posture, that keeping our mind purely on the sensation is pretty difficult.
Even from the very beginning of yoga we are working with the emotions, thoughts, body, energy, etc… We can see this by just trying to remain present with the asana and just feel. We start to learn how to control the mind by pulling our attention back to this very physical sensation. We start to learn how to work with the emotions by loosening up, relaxing into, and letting them flow without getting caught up. We learn about the energy as we deepen our experience of the stretch, feeling finer and finer aspects/qualities/fields/etc. of the body.
While yoga is a deep and vastly encompassing topic, in the beginning, just sitting down and trying to touch our toes is all we need. We do not need a mat, a ball, or anything else. Just sit down, stretch, and connect.