Whanganui mum ditches meth for marathons

A Whanganui mum is closer today to running one of the world's most gruelling endurance races.

In the last five years, Paula Johnston has shed dozens of kilos and years of drug abuse trying to achieve her goal.

"I was a drug addict so life was filled with many ups and downs, no goals, there was no fitness," she told Three's The Project.

For more than a decade, meth dominated her life. After kicking the habit she experienced major weight gain.

Ms Johnston struggled with day-to-day tasks and couldn't keep up with her kids.

"I never liked my reflection," she said.

"You'll notice tattoos over me - it wasn't to look cool, it was to take the focus off myself."

Last year Ms Johnston saw a Facebook post about a Kiwi team training to run the Great Wall of China marathon. It's 42km of rugged terrain, huge hills and all in searing heat - it's considered one of the toughest marathons in the world.

Ms Johnston couldn't even run a kilometre at that point, but she signed up anyway.

"It was huge, but I needed it. I needed something that big to aim for."

Motivational coach Doug Healey says she had "almost given up on herself".

"It was an honour to take her and add her to the team, and help her turn her life around."

The training has transformed Ms Johnston. She's now the healthiest she's been in almost 20 years.

Now she's ready to take on the Wall, but she needs some help to get there. Her sister's running a Givealittle page to get her over the line.