I got a Bosu Ball recently. Standing still on the round side in bare feet is fairly easy (I am a world class klutz, so I recognize that everybody else probably considers this "ridiculously easy"). Doing the same in ski boots is a "whoa!" experience. My legs shake so badly that you'd think there's an earthquake occurring. I'm getting better though! I watch football games while standing on a bosu ball in my ski boots. I haven't fallen through the TV yet!
I also work on my balance in sneakers all the time. I'll walk the edge of the curb, one foot in front of the other. I'll wait in line at Subway on one foot. I don't have any railroad tracks near me, so I have to pass on that one.