The British 3m springboard diver came ninth in the Olympics on Tuesday night, but his greatest victory was making it to the competition at all. Just three years ago the 19-year-old suffered a ruptured spleen while training in Australia, and came within minutes of death.
He lost five pints of blood and was rushed into emergency surgery, with doctors giving him just a five per cent chance of survival. But the Reading-born Mears came through his ordeal and managed to get his career on track - despite the 12-inch scar that runs from his breastbone to his pelvis.
With a fourth-place finish at the Commonwealth Games and now an Olympic final under his belt, he is set for a bright future in the sport.
At the age of 20 Laura Trott has two gold medals in her drawer already, yet she was lucky even to make it past her first birthday.
Trott was born a month premature and with a collapsed lung, and her parents were given the devastating news that she would probably not make it. But the Hertfordshire girl pulled through, and found her niche after taking up cycling at the age of eight - something which she only did to keep her mum company while she was trying to lose weight.
The double Olympic champion's health is still far from perfect - a chronic stomach condition means she throws up after almost every race - but she is now face of British women's track cycling.
The team pursuit gold medallist from Carshalton has suffered from alopecia areata since she was nine years old. The condition - in which the body's immune system attacks hair follicles - has left her almost completely bald ever since. She actually credits the disease with helping her succeed in the sport: she took up cycling . "I worked through any worries I had about my hair and I focused solely on that. It made me who I am," she said after winning gold.
The British showjumping legend looked set to end his career without an Olympic medal, consistently falling short for a quarter of a century despite years of success at European and world championship levels after his career took off in the mid-1970s. Then in 2000 it all looked over for good as he broke his neck in an a horrific fall that ended his career.
Two years later he decided that he had recovered enough to come out of retirement, however. He was part of the British team that dropped out of the medals after leading into the final round at Athens 2004, and finally broke his Olympic duck with a spectacular team showjumping gold earlier this week.
The Australian triathletes promising career looked in tatters three years ago: she nearly drowned during the swimming leg of a race and had to be pulled from the water. The problem turned out to be a heart defect that needed surgery, and seemed certain to end her career. She refused to give up hope, however, and won the Olympic bronze in Hyde Park - just a few yards back from a photo finish for the first two places behind Nicola Spirig of Switzerland and Sweden's Lisa Norden.
The American swimmer was diagnosed with testicular cancer the week before the Beijing Olympics. He decided to compete anyway, though missed out on the final, before returning to the US for surgery. He pressed on undeterred with his career, and won a gold medal with the US 4x100m medley team after helping the team through the heats.
The US beach volleyball star has been hit by cancer not one, but twice. He had surgery for skin cancer back in 2004, but his sporting career only took off after that and he was on course for Olympic selection until he failed a drug test in January 2010. He registered an abnormally-elevated testosterone level, but it was testicular cancer rather than doping that caused the reading.
He quickly had surgery, made a miraculously quick recovery and took his place in the US squad in London where he and partner Sean Rosenthal made it as far as the quarter-finals.