Charlotte Church - drinker, clubber, good-time girl extraordinaire - has turned her image on its head to promote healthy living.
The world-famous singer, until recently seen in celebrity magazines holding a drink and a cigarette is backing No Smoking Day this year.
Church chucked her 20-a-day habit at New Year, and apart from a lapse on her birthday, has stuck to her resolution.
But she has warned other quitters they will need "willpower".
Promoting the no-smoking message in Cardiff, the 20-year-old admitted she found it "really hard", but was motivated by changes in the tone of her voice to quit.
"I could hear a change in my voice and thought, what am I doing here? It's my profession," she said.
"I just did it through sheer willpower. I didn't have any patches.
"I was really irritable for the first three weeks. I did have a relapse on my birthday, had a few glasses of wine, smoked two cigarettes. I was really ill the next day - I won't be doing that again."
Church has her levels of carbon monoxide tested
Her Wales rugby international boyfriend, Gavin Henson, had not "nagged her" to give up, but she did concede: "He's really glad I've given up now because I don't smell of cigarettes.
"When my family comes to my house, they all smoke and I can really smell it.
"My nana has tried a couple of times and she's cut down loads so she's doing really well."
The fashion-conscious singer has seen an improvement in her skin since stopping - she said in the past her skin had felt like a TV advert "where the girl puts make-up on and it's all smoke".
Church claims not to miss smoking most of the time. However, she admitted: "The one time I think about it is when I go out and have a drink.
"I hold a cigarette in my hand but I don't light it. It's just something to do with my hands."
She has found her appetite has increased since quitting.
"After a meal I'd have a cigarette but I'd have more food now, snacks etc, but nothing I can't control," she said.
The singer, who started smoking at 16, urged teenagers not to follow her example in taking up the habit.
"The longer you smoke, the harder it is to give up. It's so not worth starting," she asserted.
And because of ever-present paparazzi photographers, Church knows she cannot get away with sneaking a "cheeky cigarette" in public.
She also fears falling back into the habit if she has just one. "If I had another cigarette now, It would be so easy to get back into it.
"I can never have another cigarette in my life."
The Welsh Assembly Government has estimated about 50,000 people in Wales will try to give up smoking on Wednesday, with around 8,000 succeeding.