The practices of yoga have the power to:
Tone the physical body, increasing both strength and flexibility
Facilitate the free flow of energy in the body
Reduce the burden of disturbing thoughts and feelings
Open a door to experiencing the bliss of life on Earth
The goal of a yoga practice is not to be able to do the physical postures like a model on the cover of a yoga magazine (though that can be a nice thing in itself!). Rather, the goal is to release our identification with the thoughts and feelings coming from the mind, so that we can live more in the present, with
greater choice in how we act, and with greater satisfaction in everything we do. It is not necessary to be flexible or be able to perform complex postures in order to attain that. In fact, anyone can attain that no matter what the size, shape, or functioning of their body. And there are yoga practices other than the physical postures!