I was once up at Lower Ottaway Lake, about 10,000 feet, when the guy I was with finally admitted that he felt lousy...and we hiked out 15 long slow milesin one day to get him to a doctor. He had bronchitis, and we were just about to go over Red Peak Pass and continue another 30 miles into the
backcountry.

And as a guide, I once had to hike a kid seven miles out because he had such bad altitute sickness that he kept vomiting. Not fun, but it is amazing what the human body is capable of doing if you take it slow.

It's important to note that in each case one of us was healthy, sane, and not stressed...so the decisions were pretty reasonable.

There should always be a plan "B"