The first thing most people say after their first sit is some version of: I could not do it, my mind would not stop. And the first thing I say back is: you did it perfectly, because you noticed.
This is not a kindness to get you through the door. It is the whole of the practice, compressed into one moment. The mind wanders. At some point you notice it has wandered. That noticing is attention, and it arrived without you trying.
Not a muscle, a return
We are often told attention is a muscle, and that meditation strengthens it the way a gym strengthens a thigh. There is some truth in that, but the image makes people grit their teeth, and gritted teeth are the opposite of what we are after.
I prefer to think of attention as a return. You go away, as everyone does, and then you come back. Each return is small and unremarkable. You come back to the breath the way you come back to a book you put down, without scolding yourself for having put it down.
The wandering is not the failure. It is the weather. The coming back is the practice.
A group session is really just a room full of people returning, over and over, quietly, at different moments. If you could see it, it would look like a pond in light rain: small rings appearing everywhere, each one settling on its own.
Where it goes
It is worth being curious about where the mind goes when it wanders, but it is not worth following it there. A thought about dinner is allowed to be a thought about dinner. You can note it, lightly, the way you might note a bird crossing a window: dinner. And then the breath, again, in the belly or the nostrils or wherever you can feel it most easily.
At the end, you will have a number, and the number does not matter. What matters is that every one of those returns happened on its own, from a part of you that was paying attention all along.