Kevin sustained a severe traumatic brain injury and was in a coma at Royal North Shore Hospital for nearly four weeks.
The prognosis looked grim: long-term dependence and nursing care for the rest of his life.
But after an amazing recovery Kevin will run the marathon on July 2 to raise money for those who helped him get back onto his feet - the RNSH neurosurgery department.
"My life changed without a warning while I was doing what I loved," Kevin said.
"That really made me realise how vulnerable we are."
When Kevin was discharged to rehab, he was unable to speak or walk, and even pointing to words on a board to express basic needs was a struggle.
It was a long journey to get better – Kevin's skull had to be reconstructed and he was re-admitted several times with complications.
"I wanted nothing more than being able to cycle again," Kevin said.
"A year later I made it back onto my bike, but I didn't feel so great about riding anymore. That's when I discovered running was for me.
"I'm feeling over the moon that I am physically and mentally able to achieve what I have after my injury and I believe anyone can do what they set their mind to."
Kevin is currently studying to become an exercise physiologist.
"I want to help healthy populations but also those experiencing conditions such as traumatic brain injuries like myself," Kevin said.
"Being active has been central to my physical and mental recovery. I like running for myself but these races I like to do for a bigger cause and give back to the people who helped me along the way."
Neurosurgeon Dr Yannis Sergides and the team at RNSH are delighted about Kevin's recovery.
"Kevin is a wonderful man and he continues to do wonderful things because our nurses and ward staff were so dedicated and skilled in looking after him," Dr Sergides said.
"To see him come from the brink to run a marathon for our cause is extraordinary and makes it all worthwhile."
Donations can be made at www.royalnorthshore.everydayhero.com/au/kevin