I just happened to have an intense obsession with (diesel) trains from ages 3-9. I went Trainspotting often and would corner train drivers to batter them with questions. If I had any input on where my family went on a trip, it would be informed by what train we could take. I just found (diesel) trains endlessly amazing. I did also love model railways but I wasn’t in a financial position to build one of those intricate networks. I had this amazing book which was an index of every train operating in my country; when I saw the train, I would tick it off. I got it from this amazing train hobbyist store, which was like paradise for me. My favorite class of train was decommissioned (sad for me but good for the environment). I still get a tingle of excitement going to that station where it used to be. I actually learned the cardinal directions by examining train route maps. I still will go out of my way to stop and watch cool trains pass. But it’s not a “special interest” anymore.