Gerry Dance, 52, suffers from Ankylosing Spondylitis, a condition where the bones in the spine and the neck fuse if regular exercise is not undertaken.
He is doing a number of running challenges this year to raise awareness of the condition.
It can take up to 10 years before a sufferer is diagnosed.
After taking on the Virgin London Marathon last year, Mr Dance decided that was not enough this time around and wanted to push the limits even more.
He warmed up for next month’s London Marathon by undergoing the multi-terrain Steyner Stinger Trail Marathon in the South Downs on Sunday.
However, even the London Marathon will seem like a warm-up as he will take on the gruelling Two Castles and an Abbey Ultra Marathon in Cyprus in May – a 50-mile mountainous course which even includes a section labelled Heartbreak Hill.
Following that, Mr Dance will tackle the Bath Trail Marathon in July, the Snowdonia Marathon in October and the 46-mile Brecon Ultra Marathon in November.
Mr Dance said: “I was lucky to get a ballot place again for the London Marathon but I decided this wasn’t enough of a challenge. I am now running, or hoping to complete, a series of crazy challenges this year!”
He is running to raise money for the National Ankylosing Spondylitis Society (NASS), the only known charity in the UK dedicated to the condition’s sufferers.
“I am in a lot of pain myself but I’m putting myself through it and at personal expense because I am passionate about NASS. I really want to make it worth all that effort by beating last years total,” he added.
To combat the fusing of the bones, Mr Dance is running every day, cramming in 55-60 miles a week as part of his training.
His wife Mandy said: “Me and our two daughters are very proud of him. He wants to raise a lot of money but the awareness is more important for him as lots of people don’t know they’ve got it.”
To donate, visit www.virginmoneygiving.com/gerrydance