I’ve personally not participated in runDisney, but I’ve been tempted! The races have a Disney movie theme. For example, there’s a Run Disney Star Wars Half Marathon on April 20-23, 2017 in Disney World.
I think the idea behind it is that training for a marathon is more fun when you get to run at Disney World or Disneyland. That would definitely up the motivation.
The racers often dress up in costumes. It’s like a running costume show! I think it would be entertaining just see the runners in their outfits.
I wondered where the runners got their outfits. Surely not everyone is that skilled at creating their own running costumes. I found a shop in Etsy called FitforaPrincessShop. Jennifer Norris, the shop owner, makes custom themed Disney running outfits. She has everything from Star Wars, Disney Princesses, Marvel Super Heroes, Beauty and the Beast, and more. I love her designs. They are runner friendly materials, without compromising on the Disney character.