I think there’s a distinction between skills that you think would be cool to have (like learning a language), and areas that you feel drawn to.
I realise this is a difficult thing for most people to tap into. But I’ve thought about this, and I think that most of my “obsessions” have come about after seeing someone else doing something poorly, and thinking to myself “I bet I could do better than that.” If I follow that initial curiosity through, it often turns into a full-blown obsession.
Finding your own 'triggers' is really important, I agree.
For me it's when I can provide help to someone. I'll easily not get anything done for a week, hear someone struggle with something that I could solve with a bit of code (often gluing various API's together), and I'll get right at it.
I'm also triggered/motivated by 'optimizing' stuff in my life. If something in my life strikes me as suboptimal and some code might be able to fix it, I'll happily try to find the least effective but most educational or fun way to solve the problem (XKCD be damned[1]). My life is filled with the coding equivalent of rube goldberg devices, and it's almost a shame that nobody can actually see them.
I realise this is a difficult thing for most people to tap into. But I’ve thought about this, and I think that most of my “obsessions” have come about after seeing someone else doing something poorly, and thinking to myself “I bet I could do better than that.” If I follow that initial curiosity through, it often turns into a full-blown obsession.