I've commented on this same phenomenon with regards to my left brain working one way while running and my right brain working another

Left Side of the Brain [looking at watch]: OK, so we're at such-and-such a pace right now, the next mile marker is X-hundred yards ahead, so if we get to that turn in so many minutes and seconds we'll be doing a something minute split which should get us to the next marker after that in such time and we'll be back home at whatever o'clock

Right Side of the Brain: What a pretty sunrise! Do I smell coffee? Ooh! I hear birds!!!

And the earworm/radio station in my head

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"What's your claim?" - Ben Gravy
"Your best work is the work you're excited about" - Rick Rubin