Roger Bannister busted the 4-minute mile limit. Once he achieved that, the limit got busted over and over again. His record-breaking run gave the world of runners hope and belief that they could do it too – and they did, many times over. The moral of the story? We don’t know what we are capable of until we push our limits. And what about those limits? I know one thing: they’re often self-imposed. Here’s an …