What if your practice is focusing on your breathing and how you stand? Stand in a really good Tadasana / mountain pose and feel the height that comes to your body as you do so. Or finish your day with a restorative pose, lay back for 2-10 minutes in Supta Virasana, Supta Baddha Konasana, Legs up the Wall, or Savasana - all without trying to fall asleep.
That can be a great
Why you ask? Because yoga is not about the bending or toning of the body. It is about uniting the mind and soul together. We use Asanas/ poses to work the body and tire it out so the body is ready to accept the will of the soul. The mind has been thinking so much about the poses that it is ready to relax and stay calm, and let the soul take over. It is this unity of mind, body, soul that we seek in yoga. There are different ways to achieve it, but as Asana practitioners, this is the path that we have chosen to try to gain that bliss of freedom.
So come where you are. If that is one pose a day, come with one pose. If it is 15 minutes, wonderful. Do what you can. My practice ebbs and flows as my life ebbs and flows, but as long as I have a practice to hold on to, then I maintain the benefits that yoga gives me, and will continue to give me as I work on Samadhi/ pure joy.