People usually run marathons for reasons other than the questionable pleasure of slogging their guts out for 42km. These can be to lose weight, manage stress or blot out failed relationships.

My reason is far less profound. I locked myself out of my apartment.

To alleviate the boredom while waiting for someone to let me in, I played on my phone and found myself typing my credit card details into the Paris Marathon website.

The last time I put on my running shoes was to toddle around the Auckland half-marathon two years ago. The next day, just as I was wondering how to reverse the €70 transaction, the deputy editor dropped Kerre Woodham's latest book on my desk.

Short Fat Chick in Paris is the follow-up to Woodham's bestseller, Short Fat Chick to Marathon Runner. In it, she documents her misery at running the London marathon last year, when she finished behind a guy in a rhino costume, then completing Paris this year.

Flicking through, I have the same reaction that Woodham says she gets from a lot of her readers. "If she can do it, I can."

Plus, the glass of fine 2007 Beaujolais that Woodham downed at the 36km mark sounds like good motivation.

Woodham likes a strong drink and has a swag of humiliating drunken tales, some of which she boldly bares in a chapter of Short Fat Chick in Paris called "Fighting the Piss Fairy".

She 'fessed up because hundreds of people had written to her after the first book with questions about battling the booze. Woodham also got Capri Clinic clinical director Tom Claunch to contribute an appendix on alcohol addiction, just in case readers needed expert advice.

That's not stopping her throwing a Books and Bubbles launch for the book at Auckland's Viaduct Harbour next weekend, at which guests can compare their freebie running gear while sipping from flutes of sparkling wine.

So, does Woodham have a problem with alcohol? "I don't know," she says. "I'd certainly drink more than the Alcohol [Advisory] Council says I should."

She can get "irritating" when she is out with friends and they'll send her home. But with an ox-like disposition, she inevitably wakes the next morning ready to juggle her many commitments as a NewstalkZB radio host, Herald on Sunday columnist, books ambassador for Paper Plus and celebrity speaker.

She certainly hasn't given up the booze to become an elite athlete. She still loves a long lunch.

At New Zealand Fashion Week on Wednesday afternoon, she ordered a bottle of Moet declaring, "Why have a glass when you can have the whole bottle?" Then she promptly shared it with all the luvvies nearby.

She works out precisely because she loves to indulge, much to the despair of her coach and the book's co-author, Gareth Brown.

"Gaz gets so exasperated and says, 'There aren't enough hours in a day to work off what you eat and drink'."

Woodham is no angel. "You don't get any prizes for being good," she says. She is comfortable with the idea that her faults inspire others.

Les Mills in central Auckland has always seemed to be a temple for the buff and beautiful. I've never had the courage to step inside. Woodham has been coming here since former Nightline presenter Belinda Todd brought her down to do the grapevine in jazzy aerobics classes.

She doesn't go near the jumpy classes now but sashays through the weights room greeting other punters.

Woodham comes to Les Mills most days, working on strength and stability with hunky personal trainer Paddy Flavell and spinning the wheels of an RPM cycle session alongside Brown.

The focus is getting her "pit pony" physique a little more thoroughbred. "If I was born slim I wouldn't give a rat's arse about being fit," she says.

Flavell takes us through weight exercises, concentrating on the abs and saddle bag areas.

He mixes up each session to keep Woodham from getting bored.

There's a lot of fluffing around, laughing and jokes slathered with innuendo, but Flavell keeps us on task. We do a few moves facing away from the mirror because Woodham doesn't want to see her "gunt" (you can use your imagination).

Woodham is strong, says Flavell. And head-strong as well. At 45, she is in a good place. Her daughter, Kate, is at university and getting married next year. Her relationship with her partner she dubs "The Irishman" is solid. Work is varied and busy.

She has not yet decided whether she will be giving the Paris Marathon another crack next year to better her time of 5hr 4min 3sec.

Brown, who built his business, Get Running, off the back of his success training Woodham for her marathons, is taking 30 runners to Paris for the event with Woodham as a host. She hosted this year too but decided to enter the race a few weeks before.

Odds are she will be packing her running shoes again next year. Woodham doesn't like to miss out.