That all changed for the Kiama mum when she had a stroke aged just 29.

Earlier this month Johnson did her longest run, a 45 kilometre trek from Kiama to Gerringong up over Foxground and Saddleback Mountain and back.

The run was a good preparation for her first ever 100 km ultra-marathon, which Johnson will run in on March 23, the day after she turns 41.

"When my neurologist, tongue in cheek, told me after my stroke to avoid overseas travel and running marathons, I took that as a sign," Johnson said.

"I played sport but never really ran for fun at the time but when I went home I thought I think I'm going to learn to run and so I did an online program, learning to run 10Ks.

"Within six months I did my first 10km fun run and then I went on to half marathons and I did that and really enjoyed it.

"To mark 10 years since my stroke I decided I wanted to run a full marathon, which I did in April last year in Canberra.

"I absolutely loved it. My face was sore because I couldn't stop smiling the whole time.

"That was so much fun but I wanted more. So, to celebrate turning 40 last year, and to mark a decade post-stroke, I signed up for the Mount Buffalo Stampede."

Johnson is now in a much better place physically and mentally but told the Mercury she felt ashamed and lonely in the immediate aftermath of her stroke.

Johnson was a registered nurse and busy mum of a five-day-old baby and three-year-old toddler at the time she suffered the stroke while out having dinner.

"Even with my history in emergency nursing, I didn't realise I was having a stroke. It was my brother who was a police officer that recognised the F.A.S.T. signs," she said.

"I remember him being on the phone to the ambulance saying 29-year-old conscious female. I remember thinking that's a weird thing to say.

"He carried me down the stairs at this restaurant to the ambulance and I still was thinking, 'no, no, no, I don't need to go anywhere' and I was fretting over being away from my bub.

"Luckily we were having dinner in Wollongong so we were just up the road from the hospital, so I was there within minutes."

Johnson is among the 145,000 survivors of stroke living in New South Wales. Regional Australians are 17 per cent more likely to have a stroke than those in metropolitan areas.

Johnson said she was sharing her story to help other people in the same situation.

"There are actually quite a lot of young people who have strokes. I just want other people to not feel as lonely as I did," she said.

"I felt I was almost ashamed of having the stroke when I first had it, which you look back at now and I know that's completely dumb.

"It was completely out of my control. So I just want other people not to feel like that too."