But, that's not why people run marathons. They run them as a contest with themselves and others in a mode of transportation that they would never actually seriously consider using except in an extreme and unusual situation such as you describe. If you interviewed all the marathon contestents, asking them why they were running it, and more than 10% or so answered "So I can better assist a loved one if an emergency arises such that I need to run really far.", I might agree with you.
CPR would probably be on my list. Gardening only counts if it's seriously done so that you can eat, not if it's done as a hobby. When I was growing up, my family's garden almost counted. :-)
5 things is difficult though, and I'll have to think about it a bit.