Just over three weeks ago my wife Rachel donated one of her kidneys to me. The good news is that she is pretty much back to normal. Now that kidneys are removed laparoscopically, she only has four tiny scars on her torso and one longer one in her lower abdomen through which the surgeons brought the kidney out.

These wounds are healing well and she tells me she is in very little pain, although her stamina is not quite what it was. I guess her body is getting used to its new internal reality.

And the good news for me is that her kidney is working brilliantly inside me. It is producing record levels of urine, has good blood flow through it, and there are no signs of my body rejecting the newest member of my internal organs.

However, as Rachel wrote here recently, things didn't go quite to plan as far as my recovery was concerned. Two days after the transplant and after several blood transfusions, they found I was bleeding internally. I became very sick indeed and had to go back under the knife for a second operation.

Although the op went well and the bleeding stopped, I was still in a bad way. My digestive system shut down and I couldn't eat or drink anything. A tube was inserted into my nose and pushed down my oesophagus into my stomach, making it possible to drain a lot of the fluid that was collecting there. I could hardly breathe and had to be on an oxygen mask 24 hours a day.

I had six intravenous tubes in my neck, a cannula in each wrist, the NG tube down my nose, and a catheter up you-know-where directly into my bladder. A ghastly white sludge called total parenteral nutrition had to be fed to me intravenously, which gave me essential nutrients and minerals to keep me going, but wasn't exactly the post-transplant feast I had imagined. This wasn't the start I wanted as the new owner of my wife's kidney.

It took a further week for my guts to come back to life. All the while my new kidney had to be kept as hydrated as possible, by passing a huge amount of IV fluid into me. My weight ballooned, even though I hadn't eaten for days, all through excess fluid. I topped out at 85kg, some 12kg (over 25lb) above what I was when I went in to hospital.

Finally, last week I was well enough to be discharged, although I have been called back into hospital every day since for blood tests and scans.

I still feel weak as a lamb and now my new kidney is free to dialyse all the excess fluid out of me, my weight has plummeted to 65kg. This doesn't create a great physique when you're 1.89m (6ft 2in). For those that have seen it, I look like Benjamin Button at the beginning of the film. My legs look as though they have been through a famine and I can barely walk. Just walking up the two flights of stairs in my flat has me gasping for air.

But I'm alive; and if Rachel's kidney continues to hold its own, there is every chance I can get back to a very good level of health. The kidney seems to be made of strong stuff, just like Rachel. As always, she has been magnificent: unfaltering in her support and care for me despite having just been through major surgery herself.

I am still in the danger zone and the team at the hospital are watching me like hawks. My body could decide to reject the kidney at any time and if I get any kind of infection, it would be very bad news. So the next two months are critical. My wife has given us a chance for a real future together - I just need my body to hold up its end of the bargain.

Thanks to everyone who has left messages of support. We hope a few people might be inspired to join the organ donor register.

• If you would like to join the organ donor register, you can do so here: uktransplant.org.uk.