When I was a kid, a "marathon" was a chewy candy bar that came in a bright red package.
I am not exactly sure how old I was when I realized it was also an event where people ran for 26.2 miles.
Ironically, once I was a triathlete, I started eating chocolate energy bars during the marathon.
Triathlon is an excuse to be a kid - at any age. Swim, bike, run - then eat tons of food.
Sounds just like childhood.