When James Brown, 32, kissed his wife Katrina, 30, that morning, he had no idea it would be their last goodbye. 

'From an early age we're told that there's someone out there for everyone, it's just a matter of finding them.  And the moment we do, our lives will change for ever.  It's a lovely thought, but growing up, I didn't believe a word of it. 

As a teenager, all I cared about was the next big party and finding a pretty girl.  Don't get me wrong, I wasn't looking to leave a trail of broken hearts behind me, but settling down wasn't on my mind either. 

But everything changed on 28 September 1996.  I was 20 and had just arrived in Salamanca, Spain, with a university friend, to study Spanish.  I'd only been there two weeks when my mate John arranged to meet me for a drink.  Even now, 12 years on, I can still remember the moment I walked into that smoky bar.  John was in the corner, swigging from a bottle. 

That's when I saw her - a girl with beautiful, curly blonde hair and the  most amazing smile.  I was transfixed and for the next few minutes, I couldn't take my eyes off her as she absentmindedly tucked a stray curl behind her ear, then threw back her head and laughed.  I must've been waiting to be served for five minutes before John caught my eye and beckoned me over. 

Her name was Katrina and, like me, she was English, aged 20 and studying Spanish at Salamanca University.  For the rest of the night we didn't stop laughing - we arranged to have coffee the following day. 

From that point, we were pretty much inseparable, but only as friends,  It wasn't until two months later that I finally told her how I felt.  Her big grin told me everything I needed to know.  We got together that night.  There was no looking back. 

Over the next year our relationship just got better and better.  We returned home to London and I got a job working for a Japanese trading house, while Katrina was working as an underwriter.  We moved in together and I felt so lucky.  She was my world.  After five years, she was the person I most looked forward to seeing every day. 

Two years later, in September 2003, I proposed and a year after that we got married with 140 guests.  We settled into married life easily and bought a beautiful three-bedroom home in Kent, which we redecorated together.  But redesigning an entire house from scratch wasn't enough to occupy Katrina and she started doing more exercise to stay in shape.  As a couple, we'd always been quite active, but over the next two years, Katrina regularly went to yoga, swimming and tennis lessons and I joined her for jogging. 

It was Christmas 2006, following three days of stuffing ourselves, when she made me promise to take part in a charity run in London as a New Year's resolution.  As we waited at the starting line of the 10km race five months later, I grabbed Katrina round the waist and pulled her in towards me.  I remember smoothing her hair away from her face, then giving her a huge hug. 

'I'll be waiting for you at the finishing line,' she joked, before disappearing into the mass of runners.  Forty-eight minutes later, I was at the finishing line scanning the crowds for her familiar blonde curls. 

Suddenly two paramedics ran past, so I followed in case there was something wrong with Katrina, not really imagining there would be.  As I moved closer I could see a medic bending over someone on the floor, blue trainers poking out from his legs.  I stopped and put my hand to my mouth.  It was Katrina.  'That's my wife!' I yelled.  'What's wrong with her?' 

At first I thought she'd just fainted, but then I saw the paramedic pressing down on her chest in short, sharp spurts as he tried to resuscitate her.  And that's when I started to scream.  As I took a deep breath in and screamed, two stewards grabbed my arms and pulled me back. 

I called out her name as they tried to move me away.  'Katrina, I'm here,' I cried over and over again.  'I'm right here, babe.'  I had no idea what was going on or why.  Feeling helpless and desperate, I tried to grab Katrina's hand as paramedics lifted her on to a stretcher.  I followed behind the ambulance in a police van to London's Guy's Hospital.  But it was too late. 

When the doctor told me Katrina had died, I felt as if my life had ended with hers.  At that point they didn't know why she'd died.  It didn't matter; she was gone and I was still here.  I couldn't take it in.  Only that morning we'd thrown on our running gear and caught the train into London, teasing each other about who would win. 

As I left the hospital, my parents asked me to stay with them, but I wanted to be in our home so that I could feel close to Katrina.  We'd left a packet of chicken defrosting on the kitchen counter, ready for our dinner. Now I was facing life alone.  You can't prepared for that, you don't expect it.

A few weeks later, a doctor explained that Katrina had died from Sudden Adult Death Syndrome (SADS), caused by an undiagnosed heart condition.  It seemed so cruel.  She did everything right - she ate well, exercised regularly.  What was the point? 

Ten days later I stood in the same church where Katrina and I had been married, this time for her funeral.  I went back to work the day after, but already I'd stopped caring about everything that wasn't Katrina.  I tried watching our wedding video just to hear her voice, but it left me feeling distraught. 

As I learnt more about SADS, I started fundraising for CRY (Cardiac Risk in the Young).  Within three weeks we'd raised £25,000 and in the  past two years, with the help of friends and family, we've hit the £140,000 mark.  Two years on, I'm only just finding it possible to talk and think about Katrina and to feel happy.  I'll always count myself lucky to have found her and loved her in the first place. 

Nothing can ever take that away. 

SADS: THE FACTS

Eight young people aged 35 and under die from Sudden Adult Death Syndrome every week and the figure is rising. 

The majority of SADS deaths are in young men - nine men to every woman. 

Close blood relatives of SADS victims should check that they don't suffer from similar conditions. 

One in 250 young people in the UK harbours a potentially life-threatening cardiac condition. 

For more information, call  01737 363 222 or visit www.c-r-y.org.uk