1. We all have our roles to play.
Watching the behavior of others, I soon realized that some people have more of a right to a seat on the bus than others—and that as a young, healthy man I'll be the last one to sit down. Even if a seat opens up right in front of me, I learned I should always give it to the pregnant woman or old man standing next to me first. At first it annoyed me that I had to do this, especially when I was tired, or in a bad mood, or just didn't want to have to stand for the hour long bus ride. Over time, though, I came to realize that the tiredness I felt could just be a fraction of the tiredness that the people I gave my seat to must be feeling. I'm not old enough yet to understand what it's like not to be young and healthy, but I should at least be sensible and realize where I fit in in society. In life we find that we've been giving certain roles, sometimes by our choosing (husband, father, friend), and sometimes not (young, healthy, man). Life needs people in all types of roles, and once you recognize the role you're cast in, the right thing to do is play it properly.
2. People don't necessarily have to have similar mindsets to appreciate each other's company.
In Argentina you describe people that make good company by saying they have "buena onda," which literally means "good waves." Someone with buena onda doesn't necessarily share the same values as you, may use more swear words than you would normally approve of, or may have different interests. But that doesn't matter. All that matters is that their heart is in the right place, that they like to enjoy themselves and they like to see you enjoy yourself, and that they're sincere and genuine. Don't worry about the faults (just like they don't worry about yours), since after all we're all just trying to get along.
3. I'm a vegetarian.
Since I was raised in a vegetarian household, I always took my vegetarianism for granted. It was just the natural state of affairs at home. In Argentina, however, staying vegetarian meant I had to actively refuse to participate with everyone else; I had to mark myself in opposition.
All my life I've grown up surrounded by a meat-eating culture. I would see my friends eating meat, and me not, and not think anything of it, reasoning simply that we were just brought up in different ways. But now I'm no longer able to say I'm a vegetarianism simply because of my upbringing. I'm free to choose, one way or another. To stay vegetarian means I must sincerely believe that it is a better way of living, and that meat-eating is worse.
4. Simply recognizing someone's presence can mean a lot.
In the US we have the bad custom of tending to ignore people we don't know in a crowd. I was really glad to find that Argentina didn't have it. If I was talking with a group of kids from class, and another kid came to join the conversation, he would say hi to me with the same friendliness that he would show to everyone else in the group. When you're in a foreign land, insecure about your language skills, lonely, not having many friends, small gestures like that can mean a lot.
5. Things take time.
I went to Argentina assuming that if I gave enough effort, I could leave 5 months later speaking Spanish like a native. Obviously that didn't happen. I tried as hard as I possibly could, but even at the end of my trip I found that if I didn't speak Spanish for a couple days I would start to lose the hang of it. It took a couple weeks before I made any noticeable improvements in the language in the first place. I now realize I can't rush it. To truly speak like a native requires multiple years of immersion, and neither sweating more nor growing unnecessary gray hairs will speed up the process.