I recently had acupuncture treatment for sciatica (or however you spell it). The guy would put the needles in and say, "now relax--try to meditate". Fat chance with those things sticking out of me in all directions. So I started to visualize chord changes on a guitar. That turned out to be an adequate distraction and it improved my playing a little. I actually invented smoother changes!! Now I do it while I am travelling on a bus or a train.

By the way, the treatment worked.

I am not sure that was multitasking though.

Murray