Justin Bieber Serenades Ellen with 'Yummy'

As a special birthday gift, Justin Bieber sang an acoustic version of his song "Yummy," and led the audience in singing "Happy Birthday." Ellen raved about the pop star's new YouTube docuseries "Seasons," and Justin discussed how being in the spotlight at such a young age affected his physical and mental health. #JustinBieber #TheEllenShow #EllenDeGeneres