You'd struggle to find someone fitter and healthier than this guy, who works as a personal trainer, competes in races across the globe, and runs up hills for fun.
It was quite a shock, then, when Garth Suthurst collapsed while running on a treadmill, suffering from a sudden cardiac arrest.
It left him with no memory of his own family, and stuck in hospital for more than a month.
Suthurst's heart was stopped for more than 20 minutes on 1 June, before paramedics managed to re-start it using a defibrillator.
The 39-year-old was rushed from the gym he works at to Costa Del Sol hospital in Marbella.
His family were crushed to find that Garth didn't recognise any of them when he eventually opened his eyes again, including his eight-year-old daughter Lily.
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But as time's gone on, he's set off on the long road to recovery and has begun to return to normal. The first breakthrough was when his family put on his music playlist, and he started to sing along with the chorus of 'Hey Jude' by The Beatles.
Garth is originally from Manchester but is now living in Marbella, where he works as a trainer at a gym. He also travels all over the world competing in obstacle course races.
He was wearing a weight vest and doing an incline run on a treadmill (for fun - seriously, this guy is fit as a fiddle) when he suffered the sudden cardiac arrest.
One of his colleagues had to drag him off the treadmill to perform CPR while waiting for the paramedics.
His partner Sorrel Lewis said: "When I turned up and saw Garth the paramedics were working on him.
"It was horrible. He'd turned blue and was cold to the touch.
"They managed to restart his heart with a defibrillator but it had been stopped for over 20 minutes."
Although doctors initially said Garth's chances of recovery were low, brain scans have showed that he has no swelling, bleeding or scarring on his brain, and he's been allowed to go home.
His family now want to raise awareness that sudden cardiac arrest can affect anyone, even someone who's as fit and healthy as Garth.
It's a similar situation to footballer Fabrice Muamba, who went into cardiac arrest on the pitch when he was just 23 years old.
In a post on the gym's Instagram, the woman who found Garth collapsed said, "The horrific trauma that Garth has suffered has been a huge shock to all that know him."
She also revealed that they would be dedicating most of the profits from their summer race to Garth.
Get well soon mate.