The most difficult thing you will ever have to do in America is learn to read English.
And you have to do it when you're five years old. You have to be done doing it by the time you're about eight years old, or you will likely be permanently behind on some academic level.
It is really, really hard to learn how to read, but it is especially hard to read English. Our language is full of ridiculous combinations of silent vowels ("question") and consonants that combine to make new sounds (g + h = f)... sometimes all in the same word ("laughter")! We have homonyms, rules that have more exceptions than the rule applies to, and a lot of other things that are terribly difficult things to get correctly as adults, much less at an age when all of your teeth are falling out.
So, thank your teachers and parents and all other adults who made sure you could read this. And congratulations for this accomplishment!
The most difficult thing you will ever have to do as a human being is learn to forgive.