Roomba roams around your space, apparently aimless, picking up old or new detritus from hard-to-reach places under the furniture. Often when I’m running, my brain roams around the space of my work, life, and relationships to bring back long-forgotten memories, things that fell off my todo list, or even brand new ideas (formed from bits of stuff that were hiding under the furniture of my brain).
Many people experience some kind of meditative state while exercising. It doesn’t happen to me every time I run. It happens more often on longer runs. It never happens when I’m not moving. Learning how to meditate has been on my list for ages, but I’ve never managed to create time or space for it. I just can’t relax.
I’m terrible at those biofeedback video games where you arrange stones in a Zen garden by calming your breath or something. My mind starts to race, the stones fly off in all directions instead of settling into a neat stack, and pretty soon I’m tearing the biofeedback sensors off my fingers and flinging them across the room.
The roomba effect is the closest I get to meditation. With my body and breath doing their rhythmic running thing, my brain somehow disconnects from my immediate physical reality and starts to roam freely in search of loose ends, until my battery runs out.
Martin Remy 
Wonderful post! I don’t know if you still feel the same, but I cannot agree more. My feet beating the ground are like a mantra that helps me focus on nothing but this.
And, yes, it works better just when you are tired enough to not being able to focus on the other things that keep your brain busy! So in longer runs.
Ah! Always better if the sun is caressing your face.