I was a single mother, working full-time as an administrator when, three and a half years ago, I discovered I had osteoporosis. I had fallen off a chair while painting my son's bedroom; it was a one foot drop to the floor, yet I broke my back in two places.

The doctors could not believe how easily my back had broken; it wasn't normal at my age. It was bad enough suffering the back injury, but eight days later a test revealed that my bone density was severely low. My bones were thinning. I had heard about osteoporosis, but knew little about it: I thought it only affected the elderly. I never knew you could get it so young: I was 36 and my bones were crumbling. I was also at risk of developing a severe form of the condition.

Doctors initially thought I would never walk again, that I would have to use a wheelchair for the rest of my life. With two children (aged eight and 10) to look after, the prospect of trying to raise a family with a condition that could leave me dependent on others was terrifying. At one point a doctor mentioned foster parents for the children - I panicked. I had visions of them being taken away.

At first, I felt I wasn't getting the right support or any constructive advice. It felt very isolating and was a particularly lonely experience. But I'm strong willed, and I was determined to pull through. I asked doctors to draw a diagram of exactly where the breaks were in my back. Every day I meditated, something I had previously only dabbled in, and within a fortnight I was discharged from hospital.

For the next three months, I wore a body plaster-cast, then after that a metal brace during the day. I was still meditating intensely and swallowing an enriched vitamin D supplement taken by many post-menopausal women with osteoporosis. My GP also prescribed the contraceptive pill Marvelon to keep my oestrogen levels high.

Six months after the accident, I started going to the gym once a week just to strengthen my back muscles. I used to loathe sport, but I realised concentrated exercise would be of great benefit. Gradually, I built up to exercising four times a week, specifically working on parts of my back. From the shoulder-press and weight-bearing exercises to stretching, skipping and boxercise - boxing, aerobics and circuit training.

A second bone density scan a year after the accident revealed that my density levels had increased. I then started taking Alendronate - a non-hormonal treatment for osteoporosis. By now I was such a regular at the gym that when a fitness instructor failed to turn up one day I was invited to teach a class for the over-60s. It was such a success that I started an NVQ course in sports and recreation to qualify as a full-time fitness instructor. I now teach anyone under the age of 100, and the majority suffer from hip or back problems and weak bones. The youngest is 17.

A big problem with osteoporosis is that many people don't realise they suffer from it until it's too late. It usually takes an accident - a break or a fracture, before most people actually have a bone density scan. Diet is of great importance. Calcium levels high need to be kept high - especially in young mothers. Now I'm very aware of what vitamins and minerals are included or excluded in my diet. I take semi-skinned milk, which is much higher in calcium than full-fat. Pilchards, sardines and whitebait are also extremely rich in it, as is sesame seed paste (tahini). Vitamin D, iron, magnesium and a host of other minerals also need to be absorbed by the body.

I'm also more aware of the risks of participating in certain activities, in case of accidental fractures. I do most things, but I wouldn't go ice-skating, skiing or roller-blading with my children. By continuing to strengthen my bones, I hope to reverse the progression.

Although osteoporosis tends to be hereditary or hormone-induced, I had no history of the condition in my family. Today, more younger women are being diagnosed with it. And per haps more disturbingly, so are children. So I am quite conscious that my daughter could have a predisposition towards it. For anyone who is worried that she might have osteoporosis because her mother or grandmother suffers from it, my advice is to ask your GP for a bone density test. I know a 14-year-old girl who is crippled and wheelchair bound by it, one woman who broke her wrist pressing a lift button and another who broke a bone shaking her toothbrush.

The earlier osteoporosis is detected, the greater the chance of controlling it. You can live a normal life. My life today is totally different. I'm so much more aware of how diet can affect us. I feel healthier and fitter now than ever. The accident and diagnosis were a turning point. I was just young enough to be able to build up bone mass for the future. Young women call me all the time to say they suffer from it and ask: "Is that it now?" But so much can be done. It's not all doom and gloom. It may be a cliché, but diet, exercise and positive thinking hold the greatest benefits.

• It affects people of all ages, including children and teenagers - one in three women and one in 12 men in the UK.

• Every three minutes someone has a fracture as a result of osteoporosis.

• Each year doctors will see osteoporosis sufferers for 70,000 hip fractures, 50,000 wrist fractures and 40,000 spinal fractures.

• Osteoporosis costs the NHS more than £1.5bn each year.

• In most cases it can be prevented by eating a calcium-rich well balanced diet, taking regular weight-bearing exercise, and avoiding too much smoking and alcohol.

• For more information on osteoporosis contact the National Osteoporosis Society (PO Box 10, Radstock, Bath, BA3 3YB; helpline: 01761 472721; www.nos.org.uk), the British Nutrition Foundation (www.nutrition.org.uk), the

Complementary Medical Association (020-8305 9871) or the Carer's National Association (0808 808 7777).