The real life fight club

It's 9am in Battersea Park; overcast, no one about. My senses are alert like an animal's, my toned body primed for the fight ahead. My attacker raises his fists and, instinctively, I raise mine. We stare at each other for a moment, a steely glare etched on my face. Then, suddenly, I swing. Left hook, then right, followed by a vicious undercut.

No, I'm not fighting off a mugger. I'm enjoying my current, brutal fitness obsession - £50-an-hour boxing lessons that have not only transformed my body, and potentially my career, but, at the age of 34, changed the person I was for ever.

The question that vexed friends and family, of course, was what on earth drove a nice girl like me to enter the ring? The answer is simple - a postnatal body that I simply had to transform. Yet so disillusioned have I become with modern, insipid forms of exercise (when was the last time you truly sweated in a gym instead of staring blankly at the TV screens?) that I knew drastic action was needed.

Motherhood had taken its toll. Our daughter, Lily, was born three years ago and our son, Sasha, arrived just over a year ago. He was a big baby and I left the Chelsea & Westminster looking like he was still inside me. I was also under contract to deliver my fifth novel the same year that I was editing my fourth, which is out this week.

Eccentrically, I share an office at home with my husband, Simon. At that time he was writing a history of Stalin. He was under pressure and moody. Lily rattled the door all afternoon begging to be cuddled. Sasha was up at night with an undetected allergy to milk. I was tearing my expensive highlights out of my head trying to write a chapter a day. For strength I scoffed chocolate digestive biscuits and raisins. Yet I looked at my body in the bath every night, desperate to lose the extra pounds. What to do?

There was no option but to get physical. Physical exercise awakens the mind, sharpens the senses, tones the body. But I didn't want to sit on an exercise bike when I could be out in the fresh air. There's little more depressing than grinding away like a hamster on a wheel, watching CNN, tiring the body and boring the mind. I'd leave feeling deflated, with a headache due to the recycled air and monotony. I tried running in Battersea Park but there is no fun in that, just a bloated red face and pounding temples. I went swimming, but got fed up doing lengths and negotiating the other automatons.

Then, just when I felt there was no way out of the wilderness, I stumbled into an oasis. I discovered Stewart Taylor at Body Architecture in Battersea. In the pale morning sunlight on the pagoda in Battersea Park, surrounded by frothy trees, a few dog walkers and the glistening Thames, we donned gloves and helmets and I fought myself to fitness. The hamster broke free and returned to nature!

With boxing, you get the incentive a game provides with the excitement of a fight; and it's one of the best all-round exercises you can do. It's both toning and cardiovascular and I quickly saw results. After the first session I awoke the following morning aching all over, like I used to after a lacrosse tournament as a teenager. My stomach firmed up, I found my waist and I no longer passed out climbing the four flights of stairs to our flat.

I got the results I wanted but also something I hadn't bargained for. You see, where one-to-one combat differs from other sports is in the way that it offers personal empowerment. Perhaps it is because of this that boxing is enjoying growing popularity among women.

Maybe we are experiencing a subconscious desire to re-connect with our aggressive inner warrior as an antidote to our sedentary lives. In history there are countless women who fought in a man's world: Joan of Arc, Boudicca, even Catherine the Great had to know how to wage war.

The Spice Girls' brand of girl power might be a glib cliche, but it contains an element of truth. Feminism has set women alongside men in the workplace. It is stressful, demanding and mentally exhausting. The modern world is frenzied, relentless - 24-hour news, communication, noise and stress. Boxing is a return to the primitive, the cure to modernism.

Like men, we need to counterbalance that mind effort with physical activity. We, too, need to let off steam. We also need to be assertive and confident. Confident people get what they want. After my boxing lessons, I feel like Uma Thurman in Quentin Tarantino's Kill Bill - I could take on an army of kung-fu assassins. Forget lessons in assertiveness, try boxing.

When I started, extra confidence was not on my agenda. I simply wanted to get back in shape. However, I realised very quickly that the sheer physicality of it fired me up. It brought out the aggressive, male side that I used to experience in my teens racing through slalom poles in Klosters or playing tennis against my brother. I realised that my life as a writer had become so sedentary and my mind so entrenched in the wartime Italy of my current book, that I barely came up for air.

Boxing gave me back my breath and with it I became more productive, more opinionated, less willing to sit quietly when I didn't agree with something. My body improved dramatically but so did my state of mind. My novel stopped being an obstacle but a challenge I welcomed.

Out of all the books I've written, my fifth has been the most testing. Not only creatively but practically, because it seemed impossible to find time to sit quietly and write. Working at home has its advantages, but also its distractions, and with a toddler and a baby I felt thinly spread and frustrated. Boxing has helped unravel those domestic trials but it has also changed the nature of my work.

The subject matter has become harder and deeper. Once curvaceous and feminine, the plots and characters received their own upper cuts, jabs and right hooks. I started The Swallow and The Hummingbird as a book about the wounds women suffer as a result of heartbreak, illness and failure: I used the analogy of two birds shot down.

One allows her wound to cripple her; the other overcomes her disadvantages and flies again.

When I started boxing, I felt the need to take that suffering one step further - for the first time, I dared to use world-historical events and awesome human experiences, and there is none greater than war. Boxing is a duel and it inspired me to write about far deadlier conflicts.

Bizarrely, my husband, the most unlikely boxer, has followedby lead and works out with Stewart as well. He has changed his body shape after 37 years of avoiding sport. He is less moody and much easier to work with. As for me, well my goal now is to punch like Uma Thurman and write like another pugilist-loving hero of mine, Norman Mailer. I'll never achieve that but at least now I'm confident it's worth a try.

For more information on classes visit: www.bodyarchitecture.com