BBC Breakfast star Louise Minchin, 50, told her 160,000 Twitter followers she will be taking on a series of challenges last week.
Today, she gave her 27,000 Instagram fans an update on her progress.
Louise shared a picture of herself in her sports gear alongside her bike in front of a mountain.
The presenter beamed for the camera while confidently posing with one hand on her hip and the other on the seat of her bike.
She captioned the post: “First sight of the fjord I will be swimming in for @nxtri #norseman and I know I have to jump of a ferry in the dark, hoping it’s smaller than this cruise ship!
“This time I am not just competing because it’s a massive challenge but also to raise money for an excellent charity, thanks for all of your support, it’s much appreciated.”
Many of Louise’s fans flocked to her post to share their support.
One user wrote: “Good luck – you’ve inspired so many to Dare to Tri!”
“Best of luck Louise. Such a difficult race to get a place but what an amazing event,” a second commented.
A third penned: “Good luck. You will be amazing. You are a complete inspiration!”
Last week, Louise Minchin thanked her fans for their support as she announced the news of her challenge.
The presenter shared a link to her donation page with the caption: “You might have noticed I have been training, this is what is for!
“Thanks for all of your support. x.”
Within the link to her donation page, she explained further details about her “toughest challenge yet”.
She explained: “It is an extreme triathlon which starts with a pre-dawn leap from a ferry into a freezing fjord, then a 180km bike ride followed by a marathon.
“Which, depending on whether I make the very tight cut off time may or may not end at the top of a mountain.
“This time, I am not just taking part because it’s an incredible challenge but also to support and fundraise for Mind, the mental health charity.
“I know many friends and loved ones who have faced mental heath problems and Mind helps people in lots of different ways.
“I know it is going to be a really tough day so thank you for your support, and donations, they will keep me going in the dark moments I will face along the way.”
BBC Breakfast airs daily on BBC One from 6am.
