In the improvising world you work at listening (which changes what passes for thought). The extent to which you continue thinking is proportional to what is accomplished musically. That probably a big part of the draw for those who can’t stop, relief from ping pong of ordinary thinking. When is the bus going to arrive, what’s the forecast, what kind of wallpaper should we get, I need a new shirt, what’s for dinner. And anyone can get that by just tuning into experiencing all sound unfolding with the same attention they might give when meditation leaders tell people to just concentrate on their breath, in and out and let the thoughts just come and go like the current of a river. The attention of not being off in a fantasy but experiencing now-ness.