Biology teacher, Mr Dyer got his running shoes on to fundraise in the first ever Stirling Scottish Marathon.
Mr Dyer has raised over £900 for the MS Society, completing his first ever marathon in three hours, five minutes and one second.
Joining 6,500 people on the day, he ran from Blairdrummond Safari Park, through Doune and Dunblane and into Stirling City Centre from the University and Bridge of Allan.
The dad-of-two had a very special reason to get involved, by honouring his own dad, who suffers from Multiple Sclerosis, a lifelong condition which can affect the brain and spinal chord.
As a keen climber, Mr Dyer has been involved in the Reserve Armed Forces since 2009 and has previously competed in Olympic distance triathlon races.
He said: "Thank you so much to everyone that has given so generously, the support has been overwhelming.
"I have been running since January although this was my first time taking part in a marathon. It went so well that I've now signed up to fundraise at the Loch Ness Marathon this September.
"Thank you also goes to my wife Rebecca, who was cheering me on at the finish line with my one-year-old twins, Oliver and Findlay."
To find out more about Mr Dyer and his fundraising mission, visit https://www.justgiving.com/fundraising/colin-dyer1