Every day for the past 18 months, Matt Daniels got up and ran a half-marathon before work.

And on the weekends? Well, he got up even earlier and … ran a half-marathon.

On Friday, Mr Daniels will reach his goal of running 21 kilometres every day for 535 days.

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It is in memory of a man he never met, Andrew Cadigan, who sold his house and walked solo around Australia raising money for charity — a journey which took 535 days.

Tragically, just weeks after completing his epic journey, Mr Cadigan was in a motorbike crash in Thailand and died.

After reading a book about his journey, Mr Daniels set himself the task of running 55 marathons in 55 days.

He accomplished it in 2016 and last year decided to embark on a new challenge which he dubbed "535 for Cad".

Mr Daniels said when he started the journey he was 20 kilograms overweight and had a six-month-old baby who was not sleeping through the night.

"I must be honest, for the first month and a half I was a little bit concerned that I might have bitten off more than I could chew," he said.

"I was carrying a little bit of extra weight, I was really tired, and I was really struggling.

"After that, it was a matter of getting it done — day in, day out — and looking forward to little milestones like the 50th one, the 100th one and then before you know it, you're ticking off some really big milestones."

Mr Daniels, a father-of-four, owns a gym in Geelong with his wife Leigh.

She said she never had any doubt her husband would achieve his goal.

"I wasn't shocked because I knew how crazy he is," Ms Daniels said.

"I knew he wouldn't not do it."

Here is Mr Daniels' advice on how to stick to your fitness goals (even if they are not as extreme as his have been).

Mr Daniels and his wife count the running shoes he's worn out during the challenge. ( ABC News: Nicole Mills )

1. Have a goal

It does not have to be something as crazy as 535 half-marathons, but Mr Daniels said having a goal could give your training purpose.

"It doesn't have to be a running goal but whatever it is, having that goal to work towards is the first step," he said.

"When you wake up and you go out to train you're working towards achieving whatever goal you have. It really helps with the training side of things and keeps you focused."

2. Find a support network

Believe it or not, Mr Daniels said there have been hundreds of mornings where he struggled for motivation.

He credited his support network, his wife, kids, and friends from the gym, with getting him towards his goal.

"They all know what you're doing and what it's all about and then when times are tough you can call on those people to get you up and about and help you through the hard days," he said.

"Sometimes I'd love to stay at home and have a coffee and read the papers and chill out but I've had to get up and get it done.

"[Leigh] is always encouraging me to get out there, get the shoes laced up and then get into it. That support has been crucial."

3. Training partners create accountability

As most of his runs have been on weekday mornings, it has not always been possible to run with training partners, but a couple of friends have regularly joined him on his weekend runs.

"Having that accountability system with a training partner or a training group really helps," Mr Daniels said.

"Knowing someone's going to be there to meet you to train for whatever you want to accomplish, that's been really helpful.

"Whether that's your partner, a family member, a close friend, a neighbour; if you both enjoy whatever it is you're working towards it's really good to have someone to help keep you accountable and help motivate you when your motivation levels are low."

4. Focus on winning the day

Mr Daniels said sometimes large goals could be overwhelming, but he likes to focus on "winning the day".

"I haven't always had the best run day in, day out, but I've always turned up and done what I have to do," he said.

"It's all about the small wins and the small wins create momentum and you can build on that momentum.

"The big goal at the end takes care of itself once you — day in day out — win the day."

He suggested if your goal was to lose weight, do not focus on the number at the end but rather concentrate on banking up small wins.

"It might be just having a healthy breakfast and if you miss the gym, not beating yourself up and getting back into it the following day," he said.

"Just commit to the day and try to win the day, one day at a time."

5. Overcome your obstacles

Mr Daniels has not had an easy run, overcoming injury, illness, a severe bout of gastro and even a car accident.

The car he was in was rear-ended by a distracted driver at more than 80 kilometres per hour, leaving him with whiplash.

"We've had some really rough patches, but I just remember why I'm doing what I'm doing," he said.

"Understanding your purpose and why you're doing what you're doing really helps get the job done."

For Mr Daniels, that is a commitment to continue to legacy of a man he never met, but whose story inspires him to keep running every day.