By the time Fiona Slade made an appointment at her surgery, she realised she was very ill. The reaction of the doctor when she walked though the door confirmed it.

"He just took one look at me and blurted out: 'My God, where do I start?'," she recalls.

"I looked like death. The illness had dramatically affected my looks. I also felt so tired that there were days when I could hardly move."

That was back in 2001 – the year in which she sold the successful management consultancy of which she was joint managing director, and also the year in which her health dramatically crashed just as she had been planning to take a much- needed break.

It was not until 2007 that Fiona felt completely well again. Today, she looks the picture of health as she talks about the guide to working and living healthily and successfully that she has just written, and the accompanying seminars she will be giving.

Using the same thorough, businesslike approach that enabled her consultancy to reach a £2.6 million turnover in just four years, she has researched information on nutrition, exercise and physiology to produce her 317-page book Work Life Body – The Indispensable Guide to You, and website www.worklifebody.co.uk.

"I definitely wish I'd had a book like this," says Fiona, who lives in Tickenham, near Clevedon in North Somerset.

"The main reason I wrote it was because I couldn't find anything like it, so I had to go to all sorts of different sources ranging from books to courses. What was important to me was how it all linked together.

"When I look back to before I became ill, I can see there were some days when I didn't have anything to drink between 7am and 7pm.

"If you're doing something like that and getting very dehydrated it can have a knock-on effect on your body, as if you're not drinking enough, or aren't eating properly it can affect your sleep."

She continues: "I didn't realise I was going to be ill. I knew I'd been at burnout level for quite a long time, but it was only when we'd sold the business that I realised how ill I'd become. It was like a massive toxic overload that was the accumulation of many, many years of not looking after myself properly. By the time I finally went to the doctor I felt that nothing was working right."

The doctor did blood tests on Fiona, and when the results came back they revealed she was seriously unwell.

Fiona's illness was in many ways surprising, as during her career as a management consultant she had always emphasised to people the importance of looking after themselves if they were to do their jobs properly.

"Health and nutrition were a huge interest of mine, and I'd always intended to learn more about them but had never had time," she says.

"As a business consultant I was always going in to talk to people about their business and almost inevitably ended up talking to them about the fact that they were suffering from stress, illness, pain, unable to sleep or had no time to get to the gym or eat properly."

Unlike many people who burn out or suffer health problems because of a demanding career, Fiona has not pursued an alternative lifestyle.

Instead, her book is very much grounded in the realities of trying to balance the demands of a job with the needs of your body.

"Stress does do extraordinary things to people," she observes. "We all think we're immune to it, but we aren't. Often the problem is exacerbated by people just keeping on doing what they do, instead of trying to find a better balance and taking better care of their health."

Fiona points out that ill health costs the UK economy £13 billion a year – as well as causing untold personal misery.

"A lot of this can be saved if people just looked after themselves a bit more and were more aware of the effect their lifestyle is having on their health," she says.

"By being more aware of how the body works and providing it with the things it needs we can make a real difference to our lives."

Fiona will be joining forces with fitness and lifestyle specialists to deliver seminars and training in the workplace on health and lifestyle, and anyone who takes part will get a copy of Work Life Body.

Work Life Body is published by Walk On and is available for £10.99.