For the 25 years that she hosted her talk show, Oprah Winfrey interviewed countless actors, authors, politicians, and everyday folks. But it's not rubbing elbows with celebrities that Winfrey's missed the most since her show ended in 2011.

In fact, when caught up with Winfrey at the New York premiere of HBO's The Immortal Life of Henrietta Lacks earlier this week, she struggled to name a single present-day public figure she wishes she could interview.

However, she did reveal what motivated her to join CBS' 60 Minutes as a special contributor.

"I felt that [the talk show] had its run," Winfrey, who stars in Henrietta Lacks and is also an executive producer, told us. "What I miss is a platform in which to hear all sides of a story."

Winfrey will make her debut on 60 Minutes this fall. The Immortal Life of Henrietta Lacks premieres Saturday at 8/7c on HBO.