It is Christmas 2004, the height of summer in the southern hemisphere, and I am in New Zealand. My friends and I are on holiday, touring the South Island for two weeks. Part of our trip is a three-day coastal walk in Kaikoura. We are walking towards the farm we are staying in on the eastern coast of the South Island. On the way we see dolphins and seals and wood pigeons. The air is fresh and the scenery beautiful. I am eager to hit the trail and confident because I have been exercising a lot lately and feel fit and full of life. I have become a health freak, eating little fat, spending forty-five minutes a day on the Stairmaster and lifting weights. I bounce and walk forwards, happy, energetic, bursting with joy. We walk at a brisk pace, chatting and enjoying the views and the sunshine.

The terrain changes and we are now walking uphill. Suddenly, things become difficult for me. I lag behind; I can no longer chat to my friends. I stop and pour out the water I am carrying. Perhaps I am carrying too much weight? I try to walk on, but something is slowing me down. I have to stop frequently to catch my breath. No matter how slowly I walk, I still have to stop.