The first thing that came to my head is "jokes". But thinking about it more, I think I came up with a better answer.

Have you ever argued with a loved on, or simply just a regular person in normal, about something meaningless? For example, try and think back on your most recent argument. You can probably remember that, right? But can you remember what it actually was about?

I can't.

Some of the common things that come to mind when I read the question is "eating healthy", "staying in shape, "meaningless jokes", and other petty things like that, that... actually do matter.

But there's one thing that people all around the world take way too seriously on a daily basis.

And that's insults.

People are people wherever you go. From the USA to Europe to the Middle East, people will insult you no matter who you are. You could be the richest, nicest and handsomest man/woman on the face of the Earth and still get insulted. Or you can be the poorest, dumbest and ugliest person ... and, of course, still get insulted. That will happen to you on a DAILY BASIS is you put yourself out in the public eye, no matter what.

If you hide your momma's basement, you might avoid it ... unless you have a thing called internet.. then you most likely won't. Scratch that, you WILL NOT avoid it.

So, you see, out of all the possible things people could take too seriously for a personal opinion, even saying a relationship is somewhat a valuable answer because "it won't last", but why won't it last? Most of the times couples break up is because they insult eachother.

If you look past getting insulted, attacked or made fun of ... well, you're going to be very successful at what you do. Personally, that's what I think people take too seriously.