As a fitness consultant and a former airman, Mark Nussey is used to tough physical challenges.

But the 44-year-old from Blundeston faces a stern test of his abilities tomorrow – when he attempts to run non-stop for 12 hours in aid of the charity that supports his step-daughter.

Mr Nussey will be running around Gorleston seafront and nearby roads from 8am to 8pm to raise funds for Mencap, which has helped his step-daughter Ella, 20, who has Down's Syndrome.

The arduous challenge – which will see him running about 65 miles – is the first of series of fund-raisers he has organised in a bid to raise at least £10,000 for the national charity.

Mr Nussey, who runs fitness classes at the Waterlane Leisure Centre in Lowestoft and served in the RAF Regiment for 13 years, is a keen runner and a member of the Waveney Valley Athletic Club.

He said: 'I wanted to do something to support Mencap as it has helped Ella by providing activity days and advice.

'The longest I have run non-stop is eight hours and I did 42 miles. I will be doing 36 laps around Gorleston seafront and each lap is about 1.75 miles so that is about 65 miles in total.

'I feel really confident about the run and feel good about it. When you're running a long time, keeping energy levels up is the key. I'll be eating porridge and bananas every two hours and having energy gel.'

As part of his fitness regime, Mr Nussey runs about 50 miles a week and he is no stranger to long-distance challenges as he has completed three London Marathons and trekked across Scandinavia.

He will set off tomorrow from Jay Jays @The Beach Café on Gorleston's Marine Parade at 8am and his partner of three years, Ella's mother Paula Lambert, will be on hand to offer support, provide him with food and drink and help raise donations.

The day will also be providing some useful training for an even greater challenge – as his drive to raise £10,000 will also see him taking part in the Marathon des Sables in Morocco.

That will see him running a staggering 156 miles over six days through the Sahara Desert in temperatures that can soar to 100 degrees Fahrenheit.

Mr Nussey recently visited Tunisia as part of his advanced preparations for the event in 2015.

He said: 'The Marathon des Sables is known as the toughest foot race in the world because of the heat and the sand. The mental strain on a race like this, with the intense heat and nothing but sand and dust for mile upon mile, can not be underestimated.

'It is not unusual for competitors to hallucinate while running and many are withdrawn due to dehydration.'

When asked if tomorrow's run and the 2015 marathon might prove too tough a challenge, he said: 'I don't let anything beat me – I don't get beaten.'

Mr Nussey was in the RAF Regiment, which defends airfields, between 1986 and 1999 and he served in the first Gulf War, Bosnia and Northern Ireland.

After moving to the Lowestoft area he became a fitness instructor at Waterlane Leisure Centre before becoming a self-employed fitness consultant.

As part of his £10,000 Mencap fund-raising drive, he will be running a four-hour spinning session at the leisure centre on Saturday, September 28 which is open to all.

To make a donation in support of Mr Nussey's 12-hour run, visit www.justgiving.com/mark-nussey

Anyone keen to take part in the spinning session on September 28 should call him on 079735 11250.