When I tell people I am learning Chinese a common reaction I get is “wow, I could never do that.”
While I appreciate the (misplaced) admiration, it’s simply not true.
There’s only one thing you need to learn Chinese (or pretty much anything else) and that is the MOTIVATION.
Let’s assume it’s not absolutely essential to your existence to learn Chinese (unlike, say, a baby growing up in China surrounded by Chinese speakers).
But for some reason, you want to learn.
When you walk into a beginner language class very few of the people you see will still be studying in a year’s time. Maybe none of them.
But if anyone is left it’s unlikely to be because they are exceptionally smart, gifted or “have a knack for languages” (whatever that means).
The most likely explanation is that they simply have a more compelling reason to be there.
The more compelling your reason for wanting to learn (ie a desire to try and understand what your in-laws are saying about you!) the more likely it is you will stick it out.
So if you meet someone who is learning something you think is impossible they probably aren’t a genius, they almost certainly didn’t “just pick it up”. It’s far more likely that they just spent many, many hours (motivated by a strong, in-laws level, force) practicing.