Just hearing about her past achievements is enough to make most of us feel tired, but Radcliffe wanted to push her body even further.
The 29-year-old has recently completed the world's first Alpine Coast to Coast.
The challenge is a gruelling expedition to climb the highest mountains in each of the eight Alpine Countries - Slovenia, Austria, Germany, Lichtenstein, Switzerland, France, Italy and Monaco - and cycle between them in one month.
"I wanted to see what I was capable of," Radcliffe tells HuffPost UK Lifestyle. "For me, it’s all about using these adventures to understand who you are, where your limits are and what you can do."
Radcliffe cycled 1669kms and climbed 141kms by foot, covering a whopping 45,530 metres of ascent - the equivalent of climbing Mount Everest more than five times.
She'd often wake up at 2am to begin her trek, and still be climbing or cycling 12 hours later. Her husband Charley drove alongside her, and joined her on foot for the climbs.
So how do you prepare for such an epic challenge?
Radcliffe was well on her way to being physically fit enough for the Alpine Coast to Coast thanks to her previous adventures, so training her mind in preparation, rather than her body, was the priority.
"You've got to make yourself emotionally comfortable with the fact that you're going to be physically uncomfortable," she says.
In the weeks running up to her departure, Radcliffe set herself a series of goals with the objective of building her confidence.
"I didn’t say ‘I’m going to race up this hill in this time’, I just went out, telling myself that when I came back I would have made progress," she explains.
Thanks to this mind-focussed training, Radcliffe was able to overcome an early setback she faced in France.
While climbing Mt Blanc, she slipped and badly bruised her leg. The injury meant she had to go back down the mountain, effectively undoing some of the hard work she'd completed.
"Emotionally, that was quite a big set back and tough to get though," she says. "When something like that happens you worry about whether you're going to be able to keep going."
After a few days resting, she defeated the mountain.
A quote that's written on a bracelet her mother gave her helped Radcliffe maintain motivation. The powerful words read: "She believed she could, and so she did."
Radcliffe began completing extreme sporting challenges about five years ago as a way of relieving work-related stress.
At the time, she had a "highly paid but very demanding" job working in business development for tech start ups.
"I found that if I challenged myself at weekends I’d have the energy and drive required to do that kind of job in the week," she says.
But as her love for extreme challenges grew, Radcliffe became more and more dissatisfied with her work.
"The challenges made me realise that if you want something, you’re the only person who’s going to make it happen.
"So many things in life that we want are in other people’s hands – like our boss giving us a promotion – but with physical challenges I feel like I can achieve anything I set my mind to."
She quit her job in the tech industry and now works as an expert on challenge safety, giving talks on how to complete expeditions without risking your life.
It took 32 days to complete the Alpine Coast to Coast - the longest expedition Radcliffe had been on previously was just three days.
Understandably, she burst into tears when the exhausting journey was over.
"I was so tired and my whole body and mind was in complete and utter turmoil," she says. "But I felt really happy and extremely proud of what I had achieved."
Next, Radcliffe wants to inspire more people to complete such challenges, and teach others the life lessons she's gained through her adventures.
"We are all more capable of so much more than we think," she says. "If you sit around waiting for something to happen, life just passes you by.
"You have to go out and give your dream your best shot, no matter what it is."