Mary Holm: Question: I've just won $28 million What should I do with it

Give almost all of it to Christchurch. File photo / NZ Herald

Answer: Give almost all of it to Christchurch. The money came from all over New Zealand, and you can channel it to where it's most needed.

I'm not being a wet blanket. Donating the money will probably make you happier than if you keep the lot.

Boosting the incomes of people who are struggling clearly makes them happier. But research shows that once people have enough to live comfortably, adding to their wealth makes little difference to happiness.

That's not to say that you won't be jubilant right now. Of course you will. But a survey of lottery winners found that, a year after their win, they were about as happy as before it all happened.

Actually, I'm surprised it wasn't worse. Imagine wondering whether every new friend you make - and perhaps even your kids - is there for you or your gold.

There's another element to this, too. While having many millions won't necessarily make you happier, the act of giving it away almost certainly will.

According to research from the University of British Columbia, "Regardless of how much income each person made, those who spent money on others reported greater happiness, while those who spent more on themselves did not."

What about the money you keep - perhaps a couple of million? By all means splurge on a big party or travel.

Then pay off any debts, including mortgages.

Invest the rest so that it boosts your income by perhaps $30,000 to $50,000 a year - whatever amount would make life easier but not hugely different - for the rest of your life.

Put the shorter-term money in high-quality bonds and the longer-term money in shares, property or a fund that holds shares and/or property. Hire a recommended financial adviser to help you set this up. Choose someone who charges you a fee rather than takes commissions from financial product providers.

That way you know they are working for you, rather than maximising their own income.