The 15th series of Strictly Come Dancing will return to our screens later this year, but a date has not yet been confirmed.
Speaking to the Daily Star, Karen said: "It was a hard time".
Speaking to his co-star, Simon said that he'd be "good at the Waltz".
Karen, 35, has been part of Strictly for the last five years alongside husband and fellow professional, Kevin Clifton.
"Strictly" bosses have been announcing this year's celebrities one by one and Simon counts "Holby City" actor Joe McFadden, Gemma Atkinson, Ruth Langsford and Reverend Richard Coles among his competitors.
Strictly Come Dancing 2017 line-up rumours: Who are the contestants this year?
As the news was announced on Sunday Brunch, Rimmer admitted the BBC dancing competition would be his first attempt at ballroom or latin.
After reading out the names of those officially taking part, the chef said: "I can probably take all of them".
Hosts Simon and Tim Lovejoy teased the big news throughout the show, leaving viewers on Twitter guessing who it could be.
He then quipped: "If you don't win, you're going to lose your place on the show".
Following the announcement, he said: "I am so excited, terrified and proud to be invited to be part of Strictly 2017".
Simon, who is best known for his hosting roles while also owning nine restaurants, continued: "I've always been a HUUUUGE fan of the show".
The 54-year-old chef revealed his involvement on "Sunday Brunch" on Sunday (13.08.17), where co-host Tim Lovejoy warned him his job on the Channel 4 show was at risk if he didn't do well. Simon, who has no dancing experience, says about joining Strictly: "Nobody will try harder, have more fun or get more out of it than me".