Please, I beg you, stop saying 'We can't afford it' as shorthand for 'no, we're not buying it' with your kids.

It's usually not true and it teaches kids that money is something that happens to you, not something you manage.

Instead, try replacing it with: 'This is not the best use of our money right now.'

Same outcome, but a very different lesson for your child to absorb.

I spoke to a group of parents at my kids' school a couple of weeks ago about raising financially savvy kids in a world that's changing faster than any rulebook can adapt to.

My main message was: principles beat rules because rules become obsolete.

Think about the advice my grandfather would have given me based on his experience: save your cash in the bank and live off the interest. Worked fine for him in the early 1990s. Not ideal in today's economy, where inflation can regularly outstrip interest rates.

We must give our children principles on which to base their personal finance problem solving, so they can make excellent choices when the game changes (and it will. A lot.)

I shared three principles I reckon give a kid a good personal finance grounding:

1. MONEY IS A RESOURCE

You exchange time for money. Wasting money = wasting the time you spent earning it. Time is the one thing you can't get back. It's a precious non-renewable resource, and you spend it without knowing how much you'll get.

2. EVERY DOLLAR IS A CHOICE

Opportunity cost is real, and every spending decision closes off other options. Getting kids to work out what they're giving up before they spend builds better instincts than any rule about saving percentages.

3. DEFINE YOUR OWN 'ENOUGH'

Our brains are wired to chase more. Without a clear picture of the life you actually want, you'll spend your whole career chasing a number that keeps moving. Getting clear on 'enough' early is one of the best shortcuts to contentment I know.