Shoes spill off a rack in the hall, a washing machine whirrs and family clutter colonises the rooms of Jane Tomlinson's home in suburban Leeds. The mother-of-three is urging her nine-year-old son Steven to finish his breakfast, brush his teeth and not to forget his dinner money. Minutes earlier, Jane's husband Mike was trying to keep the two cats Prudence and Morris out of the house. There is an urgency to the morning. Jane has to go to hospital for treatment, which involves sticking great big needles in various bits of her body, and doesn't want to have to wait hours to be seen. She hates needles and knows she will be incredibly irritable afterwards.
Jane, 42, looks like a frazzled housewife. She doesn't look like someone who does Iron Man competitions - a 4km (2½ mile) swim followed by a 180km (110 mile) bike ride and a full marathon. Some days, she can't take the laundry downstairs. Mike, 45, remarks how people always think Jane is bigger than she is. She's 5ft 3in.
In 1990, Jane was diagnosed with breast cancer. In the decade that followed she had a mastectomy and underwent two seemingly successful rounds of chemotherapy and radiotherapy. Then, in 2000, she learned the cancer had spread to her bones. It was incurable and the prognosis was that she had six months to live. In the past six years, Jane has had a total of five courses of chemotherapy and has just finished a course of the breast cancer drug Herceptin.
Perching on the edge of the sofa, Jane says that she hasn't been well. Her fatigue, just before departing for the US, is worrying. Today she begins a 4,214 mile bike ride from San Francisco to New York. Even judged by her previous accomplishments - four marathons, three triathlons and a cycle ride from Rome to Leeds - it's a challenge.
"It's the scale that's making me nervous," she says. "It's what we're doing for nine weeks. It's the sick feeling you get; it's about having said I'll do it. I feel I'm putting myself out there maybe for people to watch me fail."
The epic coast-to-coast journey has been 15 months in the planning and was dependent on Jane having a base level of fitness she could work from. "I'm not going into this thinking it will be a breeze. I'm quite frightened. I don't know the terrain. Some of the temperatures will be extreme - I mean, cycling in 45C [113F] is ludicrous. It's done on a wing and a prayer."
On this trip, she will be joined by Mike, Steven and daughter Rebecca, 18 - her eldest daughter, Suzanne, is at university. "It doesn't make it easier having Mike and Steven there, but I don't want to be away from them for that amount of time. We'll have collective memories and shared experiences - though I can imagine getting off my bike after a 70-mile day and Mike asking what we're having for tea."
The purpose of the trip is to raise money. Her gruelling endeavours have so far made £1.25m for cancer charities, and she is hoping the cycle ride will take this to £2m. "We don't seek publicity," she says. "Some glossy magazines want to do an 'at home with' feature. But have you seen the state of this place?"
Her dry self-deprecation is tempered with flashes of steel. While her endurance achievements have earned her the affection and respect of strangers, she has also been criticised for the amount of time she spends away from home. But, as she explains in her matter-of-fact way, the challenges give her goals to plan for that are not too painful to contemplate falling short of. She would like, she says, to see Rebecca through university, and would like to see Steven into secondary school - but that's an emotional investment. She never thought she would live to see Suzanne reach her 21st birthday. "If I had been really poorly and died, it wouldn't have mattered to me because I'd be dead, but it would have brought extra disappointment [to the family]."
Concerns have also been raised about the danger of setting standards by which other people with cancer will be judged. She is, she says bluntly, the most reluctant of role models: "Cancer sufferer - those two words narrow my life. As if there's nothing else to my life. Cancer is a bit of my life.
"I'm here six years after I expected to be here. People tell me I'm selfish, that I should sit at home. It's like your life has no validity unless it's for someone else's memory. It's insulting. When you're poorly, you can't do the housework, you can't do the cooking, you can't do your job. To say that you should sit in the corner so people can visit you - it's like living your own wake. It makes me a bit angry."
She laughs at the suggestion that she's stroppy, but she also seems pleased by the notion. If she has become a mascot for triumph in the face of adversity through her charity work, proving that chemotherapy and radiotherapy needn't entirely ruin someone's quality of life, that, she says, is a by-product, not something she set out to achieve.
"I am a mother, a sister, a daughter, a wife. And I happen to be a cancer sufferer. Why do I even have to be a sufferer? And what's brave about having cancer? Living with cancer isn't courageous. You make the choices you can in difficult circumstances. It's just having a shitty life. It's shit having cancer."
And the treatment that has helped to keep her alive is a double-edged sword: "I've had two rounds of chemotherapy in two years and it's bloody horrible. Nobody tells you that. Nobody writes about how awful you feel after chemo. People see your hair fall out, but that's not the worst of it. I can't feel the fingers in one hand. I can't feel the balls of my foot, which makes cycling difficult. My mouth is sore. Your diarrhoea is so bad you're pooing blood."
Listening to Jane, you begin to see how the rigours of cycling up to 90 miles a day in blistering heat might almost be a welcome distraction; something else to worry about, a different sort of pain. "You go through the treatment and, six months later, you go through it again. You do it because you know that's the only way you're going to be around for your family."
And then it's time for her to get to hospital. The needles are waiting
· To donate to Jane's Appeal log on to Janesappeal.com or call 0845 1200829.