Just want to add more context here:

For me personally, it's the uncertainty dealing with non native languages. I can see that for my own language it is so hard to take full control of all cases for even a simple word, that gives me nerve to think before I say anything non native, as I learn, there are more complex cases that makes a single word fitting to more and more scenarios. Although I totally understand that the native speakers will definitely understand even if I do it wrong, but still, I feel that nerve every time.