Some people don’t need any help finding physical challenges. They naturally and intuitively figure out ways to engage physically with the world and test their prowess. But that’s not everyone, or else we’d see people sprinting down the street, hurdling park benches, climbing flagpoles, and swinging from tree branch to tree branch. It’d be a cool world, to be sure. It’s just not the one we live in. In this world, where physical challenges are usually optional, we have to go looking for them. What are some fitness challenges to try? I’ve got 11. (This Mark's Daily Apple article was written by Mark Sisson, and is narrated by Tina Leaman)