As this is a site about yoga poses, you might wonder what "Yoga" actually is.
My own understanding is that yoga is the state of mind (or state of consciousness) where you are present. Other words for this include being in the now, the now, being in the flow, no mind.
Another way to describe it is that it is an absence of thought. You aren't thinking.
A common tendency in yoga circles is to say that thinking, and the ego that arises from it, is a bad thing. Thinking is actually necessary. It is part of what enables us to learn. It's just that we tend to think of it as the only mind state.
Flow, or yoga, is its compliment.
So if you aren't thinking, when you are flowing or doing yoga, what are you doing?
You are focusing on what is happening now. And you are responding to what is happening as it happens.
So how do you focus on what is happening now?
It helps to understand that change happens in the present moment. If someone where to touch you, there touching you is a change. You are present if you sense the touch as it happens.
That's the main reason that I focus on changes in sensation when teaching yoga. It's one of the main ways of becoming present. A simple and common example is focusing on your breathing.
When you focus on your breathing, something that is easy to focus on is the sensations generated by your respiratory muscles. Sensations include that of muscular activation. But also of connective tissue tension that is generated by muscular activation.
Since breathing is a rhythmic action, it's easy to tune into the sensations of breathing because they repeat. What you are actually learning to feel isn't your breath but the action of your muscles (and the corresponding tension that is generated by them) as they activate and relax.
And the nice thing about breathing is that you can notice not only the sensations, but the change in direction as inhales turn to exhales and vice versa.
I tend not to focus on breathing in my classes and lessons. Instead I focus on muscles in general. I teach my students to feel the sensations generated by muscles as they repeat whatever action we are working on. The result is that not only do they become present, they learn to feel various parts of their body.
We focus on particular parts in each class so that students can learn to feel and control that particular part without having to think about how to do it.
They develop habits.
With these habits, you can recognize when a particular muscle (or set of muscles) is activating or relaxing and you can (provided the muscle isn't inhibited) deliberately activate it if you chose to.
Why would you do that?
Muscles don't just generate movement or stability. They also generate sensation.
Muscles are our primary engines for sensing our body. And so when you deliberately control your muscles you can deliberately generate sensation which enables you to feel your body which in turn makes it easier to be present.
When you practice controlling muscle you develop habits that allow you to automatically control muscles (and sense them) without having to think. This then makes it easier to be present.
A key aspect of becoming present while learning to control muscle tissue comes from tai ji.
And that is moving slowly and smoothly.
This is one of the best ways of tuning into your body, at the same time it enables you to recognize patterns that you might want to override while at the same time helping you to program in desirable patterns.
Why are patterns, which are habits, so important. Habits are things that you do without thinking. They are a response to something. Habits are a necessary function is you want to stay present, if you want to do yoga.
One way to think of yoga poses is as a way of practicing being present, but also as a way of developing desirable body habits. It's a way of programming your brain. The more you practice the easier it is to do yoga outside of your yoga practice.
There's more to it than this, but in a nutshell, yoga is being present. It's where you aren't thinking because you are focused on sensing (and responding to) what is happening now.