Watch: When an 8-year-old defeated Usain Bolt

What happens when an 8-year-old personal trainer challenges the fastest man on Earth? He beats Usain Bolt wins, of course.

Ellen Degeneres invited Demarjay Smith on her show after watching his video motivating everyone to exercise and build their muscles.

At 8 years of age, Demarjay can do 90 push-ups a day! He took to exercising so that he can stand up to the bullies at his school. Push-ups and dips are his favourite forms of exercise.

When asked about what he would like to be when he grows up, he gave all the usual answers but one. He wants to defeat Usain Bolt when he grows up.

This being Ellen's show, Demarjay got the surprise of his life when Usain walked in. Ellen had a little track ready for the showdown between two men.

Usain being a sport, let Demarjay win, gave him goodies and encouraged him to keep up his exercise routine