Chris Dye, from Neepsend, performed CPR on a stricken pensioner who had come off his bike after his heart stopped in the countryside near Dore.
He then used his strength and 6ft6in frame to help paramedics, who had landed by helicopter in a neighbouring field, scale a wall with their equipment to reach the patient.
The 28-year-old medical sales specialist was this week reunited with Rod Goodfellow, who believes he owes his life to Chris and two other mystery saviours who came to his aid.
"I'm very grateful that Chris and the others stopped and that he knew what to do and had the confidence to do it," said the 79-year-old retired doctor, who is back on his bike after making a full recovery.
"Fortunately, he got some circulation to my brain which has stopped me being completely doolally. If he hadn't been there that day with his medical knowledge, I wouldn't be here today."
Mr Goodfellow says the episode highlights the importance of first aid training, which he believes should be made compulsory at school.
He also told how fellow medics believe he would not have made such a quick recovery had it not been for his active lifestyle, showing how important it is to stay fit.
Mr Dye was only last month recognised by the Royal Humane Society for his earlier 'act of supreme bravery' in leaping from his car and sprinting across three lanes of the M62 to free a man from the wreckage of a horrific crash in May 2016.
The latest rescue happened on the afternoon of September 8 this year, when Mr Goodfellow, who lives in Blackburn, had been cycling from Grindleford station in the Peak District to visit his son in Sheffield.
A female motorist saw him come off his bike after having a cardiac arrest on Hathersage Road and pulled over to help him.
When Chris arrived moments later, the patient was unresponsive, his skin had turned 'navy blue' and he was foaming at the mouth.
Using the first aid skills he had learnt in the Army Cadets and from his mother who is a nurse, Chris checked Mr Goodfellow's vital signs and quickly realised he was having a heart attack.
He and the woman began performing CPR and mouth-to-mouth resuscitation, with a second man soon joining them.
They called for an ambulance but with no notable landmarks visible they initially struggled to give a precise location before Chris had the smart idea to pass on the GPS coordinates from his vehicle's satnav system.
Paramedics landed and after Chris had helped them over the wall, they defibrillated Mr Goodfellow three times and stabilised him before taking him to the Northern General Hospital.
There he spent three days in an induced coma and another week on the wards, but he was back on his bike within a month and is now cycling up to 65 miles in one go and playing badminton three times a week.
Chris said: "It was great to meet Rod again and to see him looking so well. I'm so glad we were all able to help him that day."
Rod's son Peter said: "Everything aligned that day to allow Dad to survive. He was so lucky it happened where there were motorists passing to help him and that those who did stop knew how to perform CPR.
"He was also lucky the Air Ambulance was able to land nearby and that he was taken to an excellent hospital, where the staff did a fantastic job."
The family is keen to trace the other motorists to thank them. If you were one of those who helped, or you know the people involved, please email [email protected]