Game Changers was joined by one of the world's best-ever swimmers on Saturday morning.
Britain's Mark Foster, who mainly competed in the 50metre freestyle and butterfly events, has won gold medals at the European and World Championships as well as at the Commonwealth Games.
And Foster told Di Dougherty about his most memorable moments when representing his country, both inside and outside of the pool.
"My swimming highlight was breaking the world record for 50metre freestyle as I was the fastest human to travel through water," said the 43-year-old.
"But outside of the pool it was carrying the flag for Team GB at the opening ceremony of the 2008 Olympics in Beijing, China."
Foster was a TV expert on swimming during the 2012 London Olympics but revealed that he also got see athletes from other sports enjoy success.
"I got to watch Mo Farah race in the 5,000metres but then ran from the track to the pool to see Tom Daley win his medal in diving, so that was special as well."
To hear more from Foster, including why he doesn't like swimming in the sea, play the video above.