Ryan was born in Rowlands Gill in County Durham. After attending Hookergate School, he enrolled in the British Army at the age of 16. Ryan's cousin was a member of the reservist 23 SAS Regiment and invited Ryan to come up and "see what it's like to be in the army". Ryan did this nearly every weekend, almost passing selection several times, but he was too young to continue and do 'test week'. When he was old enough, he passed selection into 23 SAS. Shortly after that he began selection for the regular 22 SAS Regiment and joined 'B' Squadron as a medic. Needing a parent regiment, Ryan and a soldier who had joined 22 SAS from the Royal Navy, spent eight weeks with the Parachute Regiment before returning to 'B' Squadron. He spent the next seven years carrying out both covert and overt operations with the SAS around the world. One such example was the training of Khmer Rouge members to fight against the Vietnamese in Southeast Asia during the 1980s.