Okay kiddo, do you know what a coach is? It's like a teacher but for a team, they help the team get better at whatever sport or activity they are playing. Jack Daniels is a very famous coach who helped a lot of runners become better at running. He made special plans for them to follow so they could run faster and farther. He also studied how their bodies worked to make sure they didn't get hurt while running. Basically, he was really good at helping people run better.