Sophie Gannon, 25, underwent a double lung transplant at Harefield Hospital, in Hill End Road, Harefield, in August 2011.

Less than two years on, she is preparing to run the Bupa 10k in central London on Saturday next week with her younger brother, Danny Gannon, at her side.

“I’ve always wanted to do something like that, but until now, I’ve never been well enough,” she said.

“I used to lie and watch the London Marathon in bed.”

The school office assistant has cystic fibrosis, a life-shortening genetic condition which affects her internal organs.

Her health dropped to around eight per cent of a normal healthy individual before the transplant.

Sophie – who has raised money for Harefield Hospital in the past, with the help of her family – hopes to raise both money and awareness of the condition, which she says many people do not understand.

Only around half of cystic fibrosis sufferers live to celebrate their 40th birthday.

The condition causes the internal organs, especially the lungs and digestive system, to become clogged with thick, sticky mucus, which results in chronic infections and inflammation of the lungs.

“I’m used to going to the gym for lung function but frequent stomach problems in the past meant my weight was not right,” Sophie, of Abbey Wood, south-east London, explained.

“It was a big vicious circle just to keep well and my mum saved my life a few times through intuition.

“Now my weight is stable post-transplant, I’m in a better place, and for me, this is brilliant lung function.”

The inspirational fundraiser praised the care she received at Harefield Hospital on her blog: www.confessionsofacfpatient.blogspot.co.uk.

She said: “They are truly amazing, friendly, caring people, from the surgeons to the nurses right down to the cleaners and canteen staff.”

Money raised from the run will enable the Cystic Fibrosis Trust to fund research into treatments, and to support to those with cystic fibrosis and their families.

To sponsor Sophie and Danny see: www.uk.virginmoneygiving.com/team/Gannon.