This could include food, TV or social media.
For her, giving up tomato sauce would be a "real effort", but the sugar content in the sauce was high, she said.
"My food might be a little bit blander."
Another colleague is "not going to put her hand in the liquorice jar for a month".
The challenge works in a similar way to the 40 Hour Famine, where participants can look for sponsors to help them raise money.
Ms Beamsley said there was another way to raise money as well. If the "junk" normally cost the participant money, they could donate that money instead. For example, someone who drinks a $4 energy drink each day could instead donate $4 each day.
The Wanganui Cancer Society is hoping to raise more than $7,000 this year. Last year, $357,000 was raised nationwide.
Ms Beamsley said health problems, including obesity, could be a cause of cancer, so Junk Free June was a good reminder for people to live healthier lifestyles. She encouraged people to register for the challenge at www.junkfreejune.org.nz or come into the local branch for more information.
"It's really cool when people get involved with things like this, because we're not government-funded.
"Our services are getting higher and higher in demand, so we're needing a lot more money to be able to provide that service."
Cancer Society services include driving patients to appointments, visiting them in hospital, offering financial support, providing massage therapy, baking for them, helping them with the Department of Social Welfare, providing counselling services and support groups, and co-ordinating and linking other services they might need.
