I learned juggling in approximately 12minutes with a friend who knew juggling from before. He spotted me like you would spot someone in a gym: he put the balls in my hands, told me to hit one up, caught it mid flight (effectively freezing time), and told me "ok now hit the other ball up and catch this one". After 6-7 tries my brain was reprogrammed, and by the day's end we did juggling in pairs.

I guess the moral of the story is that a great teacher can push your limits way further than you could yourself? Or that it's easier to learn in a group setting?