The Atlantic's Ta-Nehisi Coates is learning French:
[T]there's no getting away from the basic feeling of complete idiocy. You are aware of being spoken to as though you were a three-year old, even though you have all the pride of an adult. Worse, if you are like me--a monolingual American in a class where virtually everyone speaks a second language and is now working on their third or fourth--you will be the slowest person. When it comes to comprehension. the Spanish and the Italians are going to just destroy you. They simply have an easier time learning to hear the language than you. This is a gift and curse. Many of the Spanish-speaking students have a much harder time learning the accent. It's as if the closeness of the two languages makes it harder--"parce que" must be be "par-ser-kay" and they will have it no other way.
The hardest thing about learning a language is that, at its core, it is black magic. No one can tell you when, where or how you will crossover--some people will even tell you that no such crossover exists. The only answer is to put one foot in front of the other, to keep walking, to understand that the way is up. The only answer is a resource which many of us have long ago discarded. C'est à dire, faith.
I've recently had the opportunity—requirement, actually—to hold conversations in Spanish, a language I have (in theory) spoken since childhood. Nothing has frustrated me more in the past two weeks than trying to express college-level concepts using my first-grade vocabulary. I also have the horrible habit shared by most Americans: I care too much about the grammar, which makes me stop and re-work what I'm trying to say. In reality, communication may not require remembering exactly how to conjugate an -ar verb in the past subjunctive (e.g., I would have conjugated it if I'd remembered how).
TNC's entire post is worth a read if you've ever tried to do this.