One hobby that didn't work out...and a bunch that did.
Hobbies other than MDing? In 8th grade I started collecting stamps but soon got bored with that, especially when I got my first MD and soon found bottles with it (and the rest is, as they say, history). Through the years got into cars, antique and transistor radios, model cars, antique toy cars, railroad insulators and date nails, records (1920s jazz, 50s-70s oldies,Beatles etc), Hi-Fi and electronics, vintage Hot Rod and music magazines, old beer & pop cans, old advertising signs, trays, thermometers, clocks,tins, oil cans, local historical photos, fixing and selling lawn mowers, attending auctions... You get the picture. And I still do all of it so I always keep busy.