"But," he writes, "the learning I got from those injuries about judging risk, heights and asking the "what if" question means I can now climb much higher and more dangerous things, like cliffs, with intelligence and survive".
However, he says, something is happening in our country that is interrupting this learning process.
It is, he says, "a sly, subtle almost unconscious change, but obvious to those conscious of it".
It is most visible in schools but it is also glaringly obvious in the sports events he enters and in workplaces.
He says it comes by many names, including cotton-woolling, nanny state, sterility and political correctness. It is, he contends, stopping us from eating dirt and learning, is slowly but surely breeding naivety - and even stupidity - and is encouraging a blame mentality and a lack of liability.
"We're losing that sense of self-responsibility and satisfaction that comes from using intelligence and personal skills to remain safe, strong and confident. We're building a world of naive dummies, lowering the intelligence of our society; we're de-evolving. We need a different attitude.
"We need to allow ourselves to eat dirt and thereby develop immunity," Gurney says.
Government departments are doing their utmost to prevent us or our children from hurting themselves and says he is becoming increasingly alarmed at the overwhelming emphasis on safety and political correctness he sees in schools. He calls it "cotton-woolling".
"I'm horrified," he writes, "to see lower branches chopped out of trees and jungle gyms ripped out of playgrounds so the kids can't climb, and lunchtime tag games like bullrush banned.
"They're trying to stop kids from hurting themselves. In the short term, it seems an admirable thing to do, but taking the long-term view, I believe we're killing them as adults.
"The Protect-icilin of the bureaucrats that was supposed to protect us from the pitfalls and storms of the wilderness, has incubated a new strain of participants who will kill themselves in their first forays into the wilderness of the real world."
Gurney says that we must let kids go back to being kids and get rid of the unwieldy burden of control.
"Nature," he says, "already has a system that automatically works. Let them climb and fall out of trees, crash their go-carts, get scrapes, scabs and stitches and the odd broken bone. They heal quickly and easily.
"Better that than letting them die, along with their passengers and other victims, at the wheel of a car 15 years on."
I heartily recommend Gurney's book, published by Random House, to all parents who care for their children's future.
garth.george@hotmail.com