If it was ever possible to summarize a continent in one word (it's not), I would choose the word tranquilo, which translates to relax. From the beaches of Brazil, to the Rambla of Montevideo, to the wilderness of Patagonia, to the rolling hills of Colombia, life here has a certain calm. South Americans can find the joys in life, have fun, appreciate the small things, and look at the glass half-full. It's due to, but not limited to, a combination of factors: emphasis on social values (family, friendship, spirituality), economic hardship, Spanish culture, weather, murky future, and my perspective as American-born Taiwanese. Not only is it applicable in principle, but I physically hear the word all the time. My Uruguayan friend was constantly telling me to slow down. Drink some mate and relax, man!

The unofficial ethos in action:

Punctuality is a well-known problem here. I haven't found it to be egregious, but it's wise to allow a +/-30 minute cushion for everything. That goes for meeting people, transportation, events, etc.
Hours of operation are suggestions. I've been unexpectedly rebuffed by many a closed door.
Long lunches are the norm. It's the biggest meal of the day and a chance to recharge. Bonus that it's also typically cooked fresh- I've never seen anyone microwaving leftovers!
You ask for the check at restaurants. The general rule of thumb is that they don't bother you, and you don't bother them. Typically, this is a win-win so you can converse without interruptions and workers aren't running around everywhere, but the attentiveness can leave something to be desired.
I spend twice as long in lines because attendants are talking to each other, or decided to do something else seemingly irrelevant at half-speed. My Spanish is good enough to know it's not a work conversation.
People walk slower. This is super subjective and specific to me, as I'm an impatient whirlwind of legs and arms.
The ubiquitous corner tiendas are more than convenience stores, they're meeting points. You can always find folks chatting, drinking, and listening to traditional music for hours.
There's no phrase or word to describe burn out (i.e. overworking) in Spanish. It's not a topic I've broached in any conversations with South Americans either.

One myth I'm slightly ashamed to admit I believed, but am happy to debunk, is that not everybody takes two-hour naps everyday. Yes, some shops close in the afternoon, but the idea of a siesta is more like a midday rest and lunch break than a midday nap, especially since school kids tend go home for lunch. In fact, I took more naps when I was working than I have while backpacking.

At home, it's cool to be busy. Every minute needs to be spent productively, we're locked to our schedules, and we want to make an impact on the world. I remember feeling guilty when I didn't have weekend plans. I remember reading articles like 'You Make or Break Your Life Between 5-7 AM' and 'Why Having a Side Hustle Leads to a Passionate Life'. I remember having a perverse pride that Amazon was known for its workaholic culture, as if associating myself with people who put in more hours somehow also elevated my own status. My upbringing in an Asian family taught me to value hard work, education, and professional success, further emphasizing this need to spend time wisely. But is it possible that we're sacrificing happiness in the name of productivity? No doubt that some aspects of the South American lifestyle has frustrated me at times, but as the product of a society where busy has become inextricably linked with success, it's stimulating to think that there's another way to live that results in surprisingly happy people.

I want to be clear that being laid-back is not synonymous with laziness, or that people are never in a rush (ahem, traffic), or are apathetic, or lack goals. My interpretation is a broad application of my personal observation, which is skewed by backpacking and the short time I've lived here. Moreover, I can't speak to the professional environment, as I haven't had the privilege of working with enough Latin Americans to develop an informed opinion. But when it comes to living life, there's some simple lessons to be learned. Have a good laugh, don't get worked up about things you can't control, enjoy time with loved ones, and live for today. Both the American and South American perspectives have taught me what it means to live a happy life, and there's a healthy friction that maintains balance. I'll gladly take the best of both.