But it is possible, life coach Louise Thompson told the Herald on Sunday.
The Herald columnist, who just launched a free e-book on resolutions on her louisethompson.com website, said any goals must be achievable "on your worst day".
"The biggest issue I see is that people set way too many resolutions and set the bar far too high for themselves. Failure them becomes almost inevitable, once we miss it one day then it becomes even easier to miss it the next and before you know it we have given it up all together.
"It's far better to set fewer resolutions with a lower bar, so you can hit them consistently, and get that positive momentum happening giving you a strong foundation to build from."
Clinical psychologist Richard Wheeler recommended keeping a journal.
Few patients took that advice, but those that did were more successful at making lasting changes in their lives.
Half a page about diet, exercise, sleep, mood, social connections and TV or device use written three or four times a week was sufficient.
And goals should be couched in positive terms, such as focusing on eating healthily, rather than losing weight, Wheeler said.
"Please be kind about how set your goals."
A three-year-old pocket rocket is at the centre of footwear designer Kathryn Wilson's resolutions for 2018.
Wilson and her husband, Liam Taylor, want most of all to spend more time with their daughter, Lola.
"My resolution is probably a family goal."
Friend Shelley Ferguson, co-host of The Block NZ and Wilson's Christmas-week holiday companion, said she didn't do New Year's resolutions.
Instead the mum-of-two, who is married to ex-Olympian Steven Ferguson, used an "overall wellbeing approach", including time in nature and yoga.
"It's lots of little things for me ... I know that I need that all through the year."