Tax law (degree and courses). It's really interesting but it's SO MUCH even by law standards. So much reading, so many textbooks, so many cases. I used to be able to really immerse myself for hours at a time but concentration has been an issue lately
Tax law was taught during my third year in law school. It was one of my favorite classes, perhaps because as an undergraduate I was a finance major. Occasionally, I still read the tax code
When I was a student each school year started around the end of August or beginning of September and ended in June of the following year. The arrival of spring ALWAYS induced a pleasant ennui, that, when I think about it, I attribute in part to a sense of being "over the hump" since June, the end of another school year, was not far off. I'm sure spring's warmer, sunnier weather was also a source of my listlessness.
So when I read your post I thought that maybe you are experiencing a weather-induced listlessness too. I do know that "So much reading, so many textbooks, so many cases" can be exhausting of one's ability to concentrate. In fact, I read so much in law school that since then, I've not been able to summon the concentration to read ANY long book cover to cover.
May your ability to concentrate soon return.