Sarah Jayne Dunn has admitted she has been "terrified" by some of the challenges on Famous And Fearless.
The Hollyoaks star has found the daring game show "absolutely nerve-wracking" at times, and been forced to face up to some of her fears.
She said: "The scariest challenge was rap running which is like abseiling but you have to go over a building facing forwards instead of with your back to the ground. It was absolutely terrifying and I'm scared of heights. So with that challenge I had to get over my fear of heights as well as learn the technique."
She went on: "But it's one of those things and you just have to get on with it."
The actress wishes she had upped her gym routine ahead of the show so she was better prepared to deal with the challenges.
"It's been a total shock to the system. It's the beginning of the year and we're doing all these crazy things. My body's going 'what are you doing? Stop it already. It's only January!'"
Sarah Jayne also defended the show against criticism, which has included Dragon's Den star Duncan Bannatyne branding it "terrible" on Twitter.
"It's a new show and it's a challenging concept. It's exciting and it's live. It's finding its feet as is everything. I think it's fantastic. We all love it and we're having fun doing something people can watch that also raises loads of money for charity. I think it's great and all my family and friends are loving it."
:: Watch Sarah in Famous And Fearless, live on Channel 4 every night at 8pm - final episode Friday, 7 January.