Walking down the street or shopping for a shirt when we find ourselves chest-to-belt buckle with some impossibly tall, muscled platinum member of the human race whose inescapable physical perfection reminds us that it's been a few days - er, weeks - uh, months - since we hit the gym.
At glittering Westfield Mall on the edge of Olympic Park, uncomfortable encounters between muscle and mush are remarkably frequent. At least here the Adonises wear team uniforms, so there's no mistaking them for regular people who are simply much more fit than you.
These are Olympians. No wonder they look better than the rest of us.
Still, it's hard to hold back feelings of inferiority, whether you are a girthful Londoner, a pasty journalist or one of the multitudes of candy apple-shaped tourists who have come from around the world to witness the games.
Flabbiness knows no borders.
"It's intimidating," said Richard Perry, a Londoner buying a soft, sugared concoction at the mall's Mr. Pretzel concession stand Saturday as two mammoth Australian Olympians strutted past. "It's like they are from a different planet."
Over there are some telegenic water polo players buying coffee and posing with fans. And wait a second: Isn't that chiseled Belgian judo fighter Daniel Fernandes, chatting with a portly security guard? And here comes a 6-foot-4-inch Russian woman in a national team tracksuit, window-shopping but refusing questions with a withering "nyet."
Hopefully, when more competitions get under way in the coming days, these Masters of the Universe will be too busy to shop, and will remain locked away in the athletes village, where mortals are not allowed to tread and we are protected from their awesomeness by a tall metal fence.
It's not that we resent them. After all, we are here to celebrate them.
But it's one thing to watch them throw a javelin and entirely another to stand waiting behind their hulking presence to buy a pair of sunglasses, nervously pretending to read something on your smartphone.
Indeed, the superhuman bodies of many of the men and women competing in the games are a stark reminder of how far the rest of us have fallen.
The host country may be expecting a record haul of gold medals from its world-class athletes, but its people really pack on the British pounds. This is the fattest country in Europe, with a quarter of the population officially obese.
A 2009 study found one in six Britons were too lazy to get up to change the channel if they couldn't find the remote, and would instead continue watching a program they were not interested in.
Americans are even more overweight: More than a third of adults are obese, according to the Centers for Disease Control and Prevention. And they are sedentary. The average American logs four hours a day in front of the television, not to mention time spent online or texting friends.
Perry, the pretzel purchaser, said he was cautiously optimistic that the Olympic Games would inspire him to shed his modest middle-aged paunch. Others were unmoved, despite the example set by the world's finest athletes.
"They look great," gushed Lucy Harley, a young Apple Store employee at the mall who insisted she was comfortable with her average level of fitness - and realistic about her laziness.
"If I wanted to look like that, I would dedicate more time to sport," she shrugged, making it clear she wasn't about to.
Elsewhere at the $2.75 billion shopper's paradise, ticket-holders gorged themselves on dark-chocolate ice-cream pops and rich cupcakes as big as a basketball player's fist. Belt-busting English beer flowed. American-style pizza was served in all its gooey greatness.
The throngs of diners at the spacious ground-floor McDonald's were at least as large and enthusiastic as the crowds that turned out to watch an Olympic cycling race through the heart of London.
Some athletes who were window-shopping as they waited for events to begin were happy to share advice - and words of comfort - with the mushy multitudes.
"In some sports, like weightlifting, we even have fat athletes," offered Marouane M'rabet, a lean Tunisian volleyballer who was sampling some massage cream that a vivacious sales clerk was enthusiastically rubbing onto his forearm.
He said anybody who wanted to get in shape should work out for half an hour a day, and insisted they would notice a difference in their physique very quickly.
Just don't expect to look like an Olympian.
"For an athlete? No. Thirty minutes is not enough," he laughed. "This is nothing."