Is that new item of clothing really going to make you happier in the long run? Do you really need to hold on to your Saturday brunch habit?
Mary Holm looks into why we spend unnecessarily and suggests how we can take more control.
She also discusses how to tell lenders you don't want to be offered loans, ideas for making Christmas less expensive, and places you can get free support to help cut your spending.
Unnecessary spending is often about a quick happiness fix, Mary tells Jesse Mulligan.
"I suggest people who do that a lot might want to make a note on the calendar or fridge to think abut their spending a month later or even a year later, think about that purchase and whether it did make you much happier in the long run or not. That can make people realise after a while they've just got a whole lot more clothes and each individual piece in the wardrobe isn't worth a whole lot to them."
Competitive spending is also a trap, she says.
"Another reason people spend unless is for the sake of appearances to keep up with the Joneses. Do we need that new kitchen? How often do we really need a new one or is it just because we are trying to impress other people?"
To get on top of your spending, she suggests people estimate how much they spend in a given period then compare that figure to their actual outgoings.
"A study in Australia found peoples' estimates of spending on transport and rent were pretty accurate – and that's not surprising, we know what the rent is – but people tended to spend more on clothes and considerably more on alcohol."
Habitual spending is an easy trap to fall into, Mary says.
"Going out for brunch on Saturday, which is a lovely thing to do, but you might want to say we'll do that every second week or set a limit. Just be aware of how powerful habits are, If you change the habit for 30 days then you've usually broken the habit."
Watch out for slogans, Mary warns.
"Slogans like 'you deserve it' ... If we want to spend the money you can always come up with a reason why we deserve it because you took the rubbish out this morning or whatever, but it's so manipulative. 'Buy now pay later' is a classic."
At Christmastime, identify what is really important, she says.
"Is it really about presents, food and nice wine or is it more about getting together?"
There's no point getting stressed and into debt just to buy the kids a lot of presents, Mary says.
"If you say 'do you want presents or not?' well, of course they going to say they want presents, but [it's more about] 'would you prefer fewer presents and mum and dad not stressed?' Children know when you're stressed and they hate it."
Drawing names out of a hat for presents or only giving gifts to children can also help keep costs down, she says.
"Or all [of you] put some money into a charity."
You can listen to all Mary Holm's money advice podcasts here.
Some resources to help manage your spending
Future me is a website where you set a goal and it will send you an email a month later to see how you went.
For people having more serious money problems, she recommends Fincap.
"Through them, you can get free confidential budgeting advice and you get a financial mentor who helps you work through your spending and debt problems. Those mentors can negotiate if you owe a lot of money to they can negotiate so sometimes you pay less in total and certainly pay it gradually. They can also help you curb spending more generally"
Debt blocker allows you to register as someone who doesn't want be offered credit.
"[It's helpful for] people who are concerned they may take out loans they can't afford or are forced to act as guarantor."
"Some people with mental health or addiction problems might want to register but to get on you have to do it through a social service agency or a JP."