I fall down distressingly often, mainly due to an old hip injury (it broke into 5 pieces one day. You shoulda seen the other guy.) and in the reconstruction process, they pieced it back together so that my gait is surprisingly normal, but there's a big wad of muscle mass missing there, so there are certain things I am never going to be able to do, like bowling (if I throw off of my right foot, my right knee buckles in towards the left just before the moment of ball release, and I hit the old drunk lady in the next lane.)
So, since that fateful day (July 6, 1998, but I am not obsessed with it or anything,) balance is shot for now and forever. And even just walking occasionally ends with me face down on the lawn or tumbling down the stairs like Mike's mayubinatorial ambitions. But on a treadmill (I do about 7 miles/week, approximately 2.5 per session three times a week,) there's a rail, and if I stumble I can grab hold, which is rare, but not impossible. I am never going to be able to reproduce that OK Go video, though. If only there were rails everywhere I walk!
Remind me to tell you all about my heart attack!