What your mind tells you as you approach 17,900 feet is,
"You may only do one thing at a time. You may choose the thing, and
you may change the thing, but doing more than one thing at the same
time is unacceptable." I chose to walk, sometimes stopping and carefully
concentrating on drinking or urinating. Then it was time to walk again.
The thing your body tells you at 17,900 feet is, "You have taken me too high.
Go down...now." We were all happy to oblige.