IMO, the lesson of the story is not that she could/should have been better prepared, but that even a trivial amount of equipment (a garbage bag) and the proper mind set can make the difference in surviving. She did not come out of it unscathed, but she came out of it alive. There is a big difference.

This is why something like the PSP can be so important. It can make the difference. Comfort? probably not. Survival? probably so.
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"Better is the enemy of good enough."