"The 40- to 49-year-olds can be the most competitive athletes. Some of them can be really stubborn and pig-headed."
The 45-year-old expected difficult conditions in Beijing but it rained on the day of the race which settled the smog, making it easier for the running and cycling legs of the race.
Sandri credits much of his success to Oamaru swimming coach Shane Jones, who works out his training programme and helps with the coaching side.
"Shane has really put some hours in with my training. Let's just say I wouldn't have got to where I am today if it wasn't for him," he said.
Sandri's feats do not stop there, either.
He's a busy man, having to juggle his intense fitness regime with being a father on top of working.
"I get up before five every morning to train and I usually like to train twice a day," he said.
Sandri now turns his sights to the Contact Tri Series in Rotorua and then to Auckland where he will try to secure a spot in the New Zealand team again.
-APNZ