You might give up alcohol in July or grow a mustache in November - but would you give up eating meat, dairy, fish, or any other food from an animal for a month?
About 50,000 people worldwide are expected to take part in Veganuary, but it is yet to take off in New Zealand.
The Vegan Society's national coordinator, Amanda Sorrenson, said she had not heard of it, but backed its message.
"31 days is a really good length of time to experience a lifestyle change," she said.
"You go through all the bumps and by the end you're starting to really feel the benefits."
She buys food from every aisle at the supermarket - except, of course, the meat one.
"I go for the beans, the grains, the tofu and the nuts, but I still get yoghurt and margarine replacements," she said.
"I get the wholefoods like bread and biscuits and crackers, jars of pickles and sauces and of course, the fresh fruit and veges like everyone else."
On Wellington's Cuba Street vegan restaurant Aunty Mena's is usually thriving.
Owner David Chai said more and more people were committing to the diet.
"I think initially we found it quite difficult because there wasn't a big market, but in recent years we're getting more popular," he said.
He said the most popular dish on the menu was a laksa - which traditionally is rice noodles served in hot soup.
"Our most common ingredients are soy and tofu, which work well for the Malaysian style of cooking."