Josh Kerr announced his goal in March and achieved it in July, breaking the mile world record. His coach, Danny Mackey, shared insights with Athletics Weekly on the journey.

Mackey knew Kerr would succeed with 350m left. Months of meticulous preparation and public commitment led to this moment. The new record is 3:42.66, surpassing El Guerrouj's 3:43.13. Read more racing coverage.

Kerr's success brought immediate attention. Mackey had to balance celebrating and preparing for the Commonwealth Games. He hopes Kerr's achievement will inspire other athletes to pursue their goals. Related: Josh Kerr Aims for Commonwealth Gold in Mile Race.

This original Runner World brief is based on reporting from Athletics Weekly. Visit the source for its complete reporting, context and any later corrections.