'I can do anything the men do.
She stands just 5ft tall and weighs eight-and-a-half stone.
Some of the equipment Marrie Prosser uses at work is bigger than her.
But the mother of two is revelling in her new-found challenging role in a traditionally male preserve.
Marrie, 29, is the only woman in Wales working on the railways - and loving every minute.
When she talks about biscuits, bars, and clips, she's not making out a shopping list - it's some of the rail speak.
The single mum lives on Merthyr Tydfil's Gurnos estate, with her two children Danielle, 11 and Brandon-Lee, eight.
She landed her job on track maintenance helping to ensure safe travel for passengers, nearly six months ago.
Marrie, who has one older and five younger brothers, aged 31 to 16 said: "The kids think it's brilliant. Danielle has written a story about me at school. My family thinks it's great - they said that not many women would get up and do what I have.
"So many people ask 'why do you do it'?
"I love being outside. I can't see me being stuck in an office job doing the same thing every day. No offence to anyone who does that, but it's just not me."
Returning to work has given Marrie a massive confidence boost and financial independence. After 11 years she doesn't need to rely on benefits to get by.
Leaving school, Marrie did get a taste of office work on a skills course but "typing wasn't for me".
While on the course, she found she was pregnant with Danielle.
After the birth, Marrie took on part-time jobs as a cleaner and shop assistant.
"Then I got pregnant with Brandon-Lee and I didn't go back to work after that. I concentrated on my kids," she said.
When her dad Charlie died in 2000, Marrie decided to fulfil her dream to become a mechanic.
"I wanted to do it at a young age but lost interest. I wanted to do work experience in a garage and they sent me to a bank!"
She'd always tinkered with cars with her father.
"He was right into cars. I was always there with him getting stinking dirty.
"After he died, I plucked up the courage to go to college and they got me a placement in an AA garage."
Marrie gained her NVQ level 2 in motor vehicle maintenance but after four years the garage closed.
"I had nowhere to go. I tried everywhere for a job but couldn't get one.
"They'd just say the position had been filled, but I felt it was just the fact I was a woman."
Marrie turned to Working Links, which specialises in helping people overcome any challenges that prevent them finding employment.
"They put me through my driving test, helped me with my CV and tried to find me a job in a garage but that came to nothing."
The knock-backs had taken their toll and Marrie was sent on a confidence-building course.
"I was talking to my adviser Leanne Sollis. It was just general chit-chat and she mentioned a course coming up involving the railways on personal track safety.
"I said 'I'll have a go at that'. Leanne asked if I was serious and I told her 'I'm 100 per cent serious, I'll have a go'.
"If I couldn't get a job in a garage, I wanted to do this.
"Within two weeks, I was on the course."
Marrie was sponsored by specialist recruitment company McGinley for the personal safety training and track induction course which prepared her for work in any part of the railways.
"I passed all the exams and McGinleys took me on.
"I started my first shift on June 1 and my life has moved forward ever since."
On Thursday Marrie completed her six-month probationary period and has to take a further test to become a fully-fledged track worker. Next month, she's on a look-out course.
"As a look out, it would be my responsibility if a train was coming to let everyone working on the track know," she explained.
"After that I have lots of other course options.
"I'm taking it one step at a time but I'd like to work my way up the ladder and see how far I can go."
Marrie works as a member of a seven or eight-strong gang.
"They couldn't get over at first how small I was," she said.
"There were nine of us together in a room for the interview.
"When I walked in they were all a bit shocked. I think they were surprised a woman wanted to do the job.
"I knew a couple of them, they live near me.
"When I first walked out on to the track on my first shift I just stood there and thought 'Oh my God'.
"Everybody knew what they were doing. They took me under their wing, showed me everything and I'm learning the different techniques they use.
"When we do anything it gets checked and double-checked.
"I told my bosses I didn't want any special treatment, to just treat me the same as they would the boys - and I think I'm proving myself.
"They were a bit nervous of me being in their environment. I was nervous of being in theirs.
"But they've got used to me, I've got used to them and we are one big happy family. We all get along and have a laugh. They're a good bunch.
"At the moment I do everything and anything that I'm allowed to.
"I do whatever the men do. I'll have a bash at anything.
"Some of the work is heavy, the men say it's heavy as well but they can carry a bit more than I can.
"We use 7lb sledge hammers, levers and huge, heavy heel bars that are bigger than me."
Marrie works a shift pattern including "the killer" 2am to 2pm stint.
She's travelled to work as far afield as Newcastle, is out in all weathers and can walk up to three miles on the tracks or "roads" as she refers to them.
Sitting cross-legged Buddha-style on her cream leather sofa, Marrie enthusiastically explains some of her work and the technical terms trip off her tongue before seeing my baffled look when she tries to make it all a bit simpler.
"We do snagging - we go behind machines that place clips connecting the rail with the sleepers, making sure they are all in correctly, tapping them in if necessary.
"I've been down pits where all the water drains, cleaning them out.
"I dig trial holes to check the condition of ballast under the sleepers.
"Last week, I was with another gang working in Ebbw Vale painting numbers and letters on sleepers.
"When the tamper comes along, the operative taps them into the computer and the machine adjusts to compress the ballast between each sleeper to the correct level."
Marrie said she found her new financial independence daunting at first. "For 11 years, I'd been on benefits then suddenly I'm responsible for making sure everything is in order."
While on her confidence-building course Marrie had to create a wish list. She's been able to tick off a job, a new car "my R reg Rover 214 is new to me" - and she's saving for a family holiday in DisneyResort Paris next year.
"Money is coming in," said Marrie. "I can live a lot better than I was. I'm not worried where the next pound is coming from or struggling to give my kids the best I could so that they would not be any different to other children
"I wouldn't swap the job now, I'm happy where I am. People ask how I can enjoy going to work. But I really do. I'm doing something different all the time."