I had another one of those, “why on earth am I learning this language!” days yesterday. This came as I was writing out conjugations of verbs to fill in a chart.
First, I learned the polite conjugations. You know those guys, right? －増す、－ません、－ました、－ませんでした. I’ve been using them for months.
Now, I am learning the plain conjugations: －う、－ない、－た、－なかった.
I filled out a whole chart full of those guys, and then I turned the page and what did I find? Another chart, this one full of adjectives to conjugate: －い、－くない、－かった、－くなかった.
Whew! It was at this point, trying to keep the various conjugations straight in my head, that I asked myself for the zillionth time, “Why on earth am I learning this language?!”
Well, because I want to. That’s really it. I don’t have any external motivation, really. I just want to.
Keep in mind that this moment of frustration doesn’t mean that I am giving up. I wrote the above words yesterday, and, this morning, as I refilled my glass of tea, I said, 「冷たい紅茶だ。」 Did you notice the use of the plain verb there? Woohoo!
I would just like to confirm that, from the standpoint of a native English speaker, Japanese is, in fact, a crazy language. It is also a lot of fun to learn and is absolutely learnable. (I don’t think “learnable” is actually a word, but, what they heck, you get the idea.)