Fly the kite on the top of Mt. Whitney
It was a long long hike/climb. We made it all the way to the top, 14,500 feet! It took two days to get there and conditions were much tougher than expected. Weather forecast called for "Blustery" conditions, but there were also icicles in our tent. We flew it (kinda) :). We were pretty exhausted by that point, and suffering the effects of altitude impairment. Keep in mind there is little oxygen way up there, almost 3 miles above sea level. After the video was shot, we needed to make a hasty decent to keep as much daylight as possible and traversed most of the 11 miles to the trailhead in the dark with headlamps. Matt said this might have been the toughest endurance exercise he's ever done.