We may imagine we're bullet-proof, but life's dangers are always lurking.

I started writing this column at the beginning of the week. I wittered on about how a magnificent oak tree which shaded my house had fallen over.

I loved this cathedral-like tree which formed a canopy over my deck and made me feel like I lived in a treehouse.

You could watch the seasons change as its leaves turned - the magic of bright green leaves unfurling after the bleak beauty of winter.

But after a recent storm I heard an enormous crash and looked outside to see my beloved giant had fallen over, its root system undermined by the storm.

I wrote about all this and then the Christchurch earthquake happened and I seemed like a total dick to be whining about a lost tree. Blah blah blah, who cares. But strangely, the point I was trying to make about risk may be apposite.

We live in times where we are able to delude ourselves a lot of the time that we can manage the risks in our lives. We are in denial, like David Foster Wallace's fish.

"There are these two young fish swimming along and they happen to meet an older fish swimming the other way, who nods at them and says 'Morning, boys. How's the water?' And the two young fish swim on for a bit and then eventually one of them looks over at the other and goes 'What the hell is water?"'

We function on auto-pilot where most of the time - even in business - we have the luxury of making assumptions that life will be safe and ordinary, forgetting how risky it is.

As economist Brent Wheeler pointed out, in the recent Close Up exclusive interview with disgraced Hanover boss Mark Hotchin, the word "risk" was never mentioned once. It may take a tragedy to shock us out of complacency and remind us how feeble we really are.

Oh, I know we all put on sunscreen and wear bicycle helmets and angst about some risks - but maybe the wrong ones.

As Psychology Today says, faced with a precipice or a predator, the brain is biased to make certain decisions, reflecting the choices that kept our ancestors alive.

But we don't have cognitive shortcuts to deal with new uncertainties. That means we fear snakes, not cars and are anti-pesticide - unless we put it on our own garden.

We are scared of other people talking on cellphones while driving but happy to do it ourselves (we prefer risks we think we control).

We speed up when we put our seatbelts on (substituting one risk for another); we fret about teens smoking pot, but not about injuring themselves playing sports (risk and values are all messed up together); we love sunlight but fear nuclear power ("natural" risks are easier to accept).

But perhaps the most helpful thing you need to remember about risk is quite simple: to just try not to forget that it is there all the time, in business and in life. If one good thing could come out of the Christchurch earthquake it might be that in New Zealand right now we are fully awake and cognisant of just how fragile life is.

We are all hugging our children tight this week.

Hang on to this feeling. Because as life returns to normal, as hopefully it will, it is so easy to slip back into our default "What the hell is water?" setting.

I need to keep reminding myself how grateful I am the tree didn't fall on my 6-year-old daughter asleep in her bed, next to the window, right next to the tree.