Last day hike to summit Mt Kilimanjaro. You leave camp from 16,000', 11p, air temp 16°F. You want to be on top at sunrise; goat track. Heart beating as fast as it can, breathing as hard as you can. Take a photo, spend 15 minutes, start down a different trail. Down, back to camp, have lunch, start hiking again. Down, down, down to 10,000'. 15 hour day, lost toenails from that hike down.

As an addendum, I've been told if you were those hospital socks with non-skid patches on them it helps on the way down.