It seems like lots of people have their own approaches and ideas. The way I do it, and I don't do it nearly often enough, is like this:

I close my eyes, and begin to take in a slow, full, deep breath.

As I inhale I think about everything in my mind, consciously tagging every worry and idea floating around my head. I stimulate them into noise

By the time my lungs are full, my mind is a cacophony. I linger before i exhale, savoring this moment of anticipated release, a brain full of sound and thought, all of it about to die a temporary death. It's like being on the top of a roller coaster.

Finally I exhale, and it's like pulling the plug of a bath or blowing out smoke. Everything held in my head (or just some of it, and thats okay too) flows out of me and is carried away on the wind. For one sublime moment, nothingness reigns. New thoughts crop up almost immediately of course, it's like digging a hole in sand; it fills in quickly, but you get momentary glimpses of what lies beneath.

Then I start inhaling again, stoking my worries to louder and louder self-expression to heighten the pleasure of their purging.

I'm audhd, and when I get super focused in on something for many hours until my head feels too heavy, this helps lighten it up again.

After some predetermined number of breaths (I hate the idea of trying to meditate with a ticking time waiting to removedme) I open my eyes feeling renewed