A necessity: In the Antarctic, Arctic and high into the Himalayas, I've found the necessity is a sleeping bag rated to at least -40F.

A luxury: A jar of Bovril. For a quick fix when you're cold and exhausted, a scalding cup of Bovril tastes like a feast.

A good-luck charm: I always take a relic of St Therese, a small bone fragment in a glass case. I was given it for being a member of a winning Catholic Football League team when I was young. They didn't give medals, only saintly parts as prizes. The bishop who blessed it said the person wearing it would never die of unnatural causes. At the age of nine, that made sense. Well, I'm still alive, so who knows.

If only: To be honest, in the extreme sports arena, the harder the conditions the better. It's all about surviving extreme temperatures, days without food and rest, distance travelled, near-death experience, etc. That said, there is one thing I would like to see invented: a better seasickness medication. There is nothing so humiliating and terrifying as being trapped at sea, curled in the fetal position, believing your boat is about to capsize.

• Michael Collins is a novelist and extreme sports enthusiast. His latest novel, The Keepers of the Truth, is published by Phoenix House at £9.99.