K-pop: 'Not knowing if I'd make it was the hardest part'
Newsround has been to South Korea to find out more about K-pop - the Korean popular music that is taking over the world.
We went to meet iKON, a successful group in South Korea, to find out more about how people become stars in the industry.
"Some people train for around 10 years," explained Donghyuk.
Song said that the hardest part was doing all of the training without knowing whether or not he would be a success.