I think that am_Unition unwittingly helped me with the specialisation choice: plasma physics. Thanks, man! :D
Last week was all about reading about stuff that I had an only vague understanding - statistical physics (Ryogo Kubo's and Landau-Lifshitz books are worth recommending), fluid dynamics (again, Landau-Lifshitz) and of course the introductory plasma physics (Montgomery and Tidman seemed like the most approachable choice at my library). I forgot about my date, board games, programming project and even my self-imposed PT regimen. That's unusual for me, to say the least.
Anyway, it's great! It utilises some of my favourite parts of mathematics all while forcing me to bend over backwards to understand what's happening. Even if I would end up doing something completely different, it's pretty much the best mental obstacle course I had in a long while. Possibly ever.