A YEAR ago I staring death in the face. The spinal cord tumour removed in 2010 had returned and was on the nerve root which runs to the lungs. The surgeon told me there was the risk that I could lose both lungs and spend the rest of my life on a ventilator. There was a high chance I could lose function in my arms.
I had surgery last October. They cut through the back of my neck and that coupled with the muscle removed to get into the spinal cord has left me in excruciating pain most of the time. It's difficult to know if that will get better.
The good thing about being on a bike is that the pain from surgery is masked by the pain of cycling. The latter pain makes me feel alive. I thrive on that. After every training session I feel grateful I still have my lungs and didn't end up in a wheelchair.
Sport has always been part of my life. I started off playing shinty in Newtonmore near Aviemore. I did skiing and represented Great Britain in karate. I dreamed of being an Olympian but karate wasn't an Olympic sport.
I moved to athletics and won an East of Scotland 400m title. When athletics didn't work out – I was competing in the Scottish Championships when a bone in my foot snapped [due to a stress fracture] – that led me to try bobsleigh.
I made good progress in bobsleigh but was constantly ill in the year leading up to the 2006 Winter Olympics in Turin. I missed out on the qualifying standard by one hundredth of a second. I told myself I had to close the door on my Olympic dream because I wasn't getting anywhere.
I was born with clubfoot and came close to having my right foot amputated as a baby. I was working with a physiotherapist to try and get more movement. She mentioned working with Paralympians who had similar problems.
I contacted the British Paralympic Association and was invited along to a talent ID day where I was tested for rowing. That was 2009. A few weeks later I had my first session on water. Five months after that I won gold at the World Championships. I do believe it saved my life. If I hadn't taken up rowing there is no way the tumour would have been discovered. Over time I would have slowly lost motor skills, function and died.
The surgeon believes that the tumour developed in the womb and is linked to a faulty chromosome. I had symptoms my whole life but every time I visited a GP they put it down to doing too much sport or simply growing pains. 
The blessing of taking up rowing was that the support team picked up on my problems. I was sent for a scan in 2010 which is when the tumour was found. A week after the first surgery a blot clot started to form. I woke up paralysed from the neck down. I was rushed back into hospital for a second surgery. If that blood clot had continued to grow it would have killed me.
The gold I won at the 2012 Paralympics in London was based on an unhealthy obsession. I wanted it so badly that when I crossed that line I basically lay back in the boat and thought: "Thank God that is over." It was almost a relief. It wasn't an enjoyable process and stressful. The race itself was hell.
I have since worked with a sports psychologist and realised that obsession wasn't built on any values. What I have done differently for Rio 2016 – where I hope to compete in cycling – is to build a goal not an obsession. It is based on the strongest of my values which is gratitude.
When I found out the tumour had come back last year I set myself a four stage plan: surgery, rehab, cycling up Mont Ventoux and Rio 2016. I heard about doing three assents of Ventoux in a single day. There was one guy who said: "There is no way he will climb it." I thought: "Cheeky so-and-so." I wanted to prove him wrong – and I did.
Every five months I go for a scan. I'm waiting for results at the moment and petrified about that. All I want is to get on with training and live as normal a life as possible. I realised I have two races: one on the bike and the other with a tumour. I need to win both of those.

Follow David Smith on Twitter at @DSmithGB