"After a while, you start to go on automatic pilot," Cowell told Oprah Winfrey during an interview Thursday. "And there were too many times, Oprah, where I was sitting there bored, and I thought, 'The end of the day, the audience doesn't tune in to watch me being bored. They deserve more than that.' But I can't hide it when I'm bored. I just can't fake it."
The 50-year-old British music executive, who said he always promised himself that he'd leave before he was forced to go, hopes his replacement won't just be a brash personality.
"I think, primarily, you've got to have somebody on that panel who actually knows what they're talking about because everyone is talking about casting the nasty person or this person or get another Brit in," he said.
Cowell also discussed how taxing the show and all the attention have been. "My year is like a yo-yo. I mean, I go through up and down moments ... so I'm very dark when I'm in those moments," Cowell said. "Maybe it's the draining effect when you have a lot of people who depend on you ... And you just become aware that a lot of people depend on you, rely on you, or you're not giving people the time you should be giving them. It's almost like a guilt thing. And that does drain me."