A friend recently asked me to speak to someone just out of hospital paralysed by a spinal cord injury. He is struggling to come to terms with the changes in his life. What am I to say to him? How many of us can gulp in and digest the awful truths immediately: no more walking, no more feeding yourself or drinking from a cup unaided, no more reaching out to your loved ones, no more sensation of hand against warm skin, no more able to give a reassuring squeeze or hug. Just a dreadful isolation in the steely straitjacket of your own unfeeling body.

And then the indignities of losing control over your bowels and your bladder and all hope of sexual release - if only desire would also cease to torment, but your head goes on, remorselessly.

I cannot lie to him, but dare I tell him the truth? Dare I say, "What you have lost is almost unbearable. No one has a right to insist that you bear it. But if you choose to live you may as well squeeze life for everything it has to offer because grief will always be there, threatening to overwhelm you."

It took me some time to be that honest with myself and routine events can push me over the edge, such as the recent turning of the year into year four since I broke my neck in Bolivia. One moment I can find myself enjoying a lively New Year's dinner party with friends, the next feeling hopeless and crying uncontrollably with grief for the very first time. The effect of this on those close to me was devastating and I can see it would become a terrible burden if it happened too often. There is a fine line between expressing what you really feel and indulging in self-pity - not an easy line to walk.

And then, a couple of days later, a friend sent me an article from the New Yorker magazine telling how, in China, a promising therapy for spinal injury has moved from human clinical trials to an operating programme that already exceeds 300 people. The huge surge of elation I felt had to be brought under control with rational caution. The ordinary rollercoaster of life exaggerated by these huge peaks and troughs.

Life for someone with spinal injury has its ups and downs like anyone else's, but with added intensity. It was wonderful when I overcame the image of victim in the eyes of my children - becoming "Dad" again, confidant, a problem solver, a source of support in crisis. The accident reconnected me to my brother as we brushed aside the sullen estrangement we had allowed to creep over us. I love talking with friends again now they are no longer afraid to disagree with me and give as good as they get. Especially when accompanied by too much wine. Most of all, in bed, I enjoy talking to my wife in the intimacy of night when all the carers have left.

And then there are the simple things in life, awkward to do but giving greater satisfaction: going to the theatre and the cinema, taking a drive into the countryside, even the simple achievement of going into town on the bus. I can connect to the world through my computer, read books, papers and magazines online, write with voice-activated software, make and receive phone calls independently and contribute to the mundane tasks of household management. I can dare to have real plans for a real future.

This positive outlook can easily be undermined by such tedious irritations as having to be repositioned in my wheelchair after a spasm. I mourn the loss of spontaneity, even in ordinary things such as going to the local shops. Mornings and evenings are governed by a rigid, time-consuming regime, and I can never truly be left alone as my blood pressure is so low that even eating a sandwich can make me feel faint - the postprandial dive! Always lurking is the constant fear, however irrational, of being sidelined, becoming an old man in the corner, suffering loss of respect, sinking into isolation.

So what do I say to my friend's friend? How will he ride this rollercoaster of uncertainty? Should I try to protect him from too much of the harsh reality? Would it not be better for him to be prepared? At least my story has texture, neither cold bravado nor corroding loss of hope. My life has made real gains to counteract the terrible losses, though it is impossible to draw up a balance sheet when gain and loss are so incommensurate. I want my body back but I would not be the man I was before, even if it were possible.

So honesty it had better be, and at the end I will say, "Your life is not over, you are still you, you haven't gone away. Be strong and people will realise it soon enough."