my biggest "pooped" situation came when - due to inexperience - I hit an uphill unprepared - didn't downshift enough and pretty much came to a stop. I just couldn't pedal/move my legs. Of course, I then proceeded to tip over with my feet clipped into the pedals (still getting used to clipless) cause I panicked. Didn't really hurt, but I learned my lesson about shifting to the easy gears.