So in 2008, then aged 38, Karen resigned from her senior role at banking group Barclays.
Also learning to live with type 1 diabetes, she and her husband travelled around the Caribbean, Vietnam and Thailand for six months.
Belu had been founded by filmmaker Reed Paget, who stepped down from the top job for Karen to replace him.
“Clearly it wouldn’t have been the easiest time for either of us, but we did lunch and cleared the air. And Reed wanted nothing more than to see Belu become successful in a sustainable way,” says Karen.
“When I joined Belu it was in debt and it wasn’t sustainable. We could have wound up completely – it was time to move on. So we kept the name, but everything changed.”
Her business plan was so successful that sales have since soared, with annual revenues of £5.9m in 2015. And since 2011 Belu has donated more than £1.5m to WaterAid, the global charity that aims to give more people in the developing world access to safe drinking water and good sanitation.
Karen says that hotels and restaurants were keen to come on board because they welcomed Belu’s commitment to environmental best practice, which she decided to strengthen and promote as much as possible.
In addition to being carbon neutral, and donating to WaterAid, the company’s bottles are made from recycled glass and plastic.
“It was important to demonstrate we’re doing this properly. First and foremost about our social and environmental mission, and secondly through building sustainability by giving our profits to WaterAid,” says Karen.
She adds that Belu forms relationships with restaurateurs who “buy into our mission”, and whose customers are pleased to see the Belu name because they understand and appreciate the work it does.
Karen says that this is better than “fighting for [supermarket] shelf space, and having to fund promotions to move goods from the shelves”.
“Last year was the year from hell. I had breast cancer – thankfully I didn’t have chemo, and I kept my hair,” she says. “I was exhausted and knackered over the summer, but my team really stepped up.”
She adds that when she was really exhausted during that difficult time, she would remember that life was still worse for a “six-year-old walking eight hours a day to collect water”. This made her realise that having to deal with her bad news was “no big deal”.
To help limit Belu’s carbon footprint, Karen encourages her 34-strong workforce to work from home when possible, to remove the need to commute. She herself lives in rural Warwickshire, and usually goes into the office in London only two or three days a week.
“The rule is not to go into the office when you can work at home.”
He adds: “Its targeting of the hospitality sector and its innovative approach to reducing the environmental impact of its products has driven demand from clients eager to improve their image through corporate sustainability.”
She recently took part in a panel discussion for the Chivas Venture, a competition for aspiring social entrepreneurs organised by whisky brand Chivas Regal.
“I love this part of my job,” says Karen, who is married with two children. “It reminds me that I’m not a complete disaster, and reminds me of the progress we have made.”
“Launching and running a social enterprise is a wonderful, aspirational thing to do. It’s using your skills to do something amazing, but in reality it’s harder than you think.”