Flying
I am currently working on my pilot's certificate through Flying JTD. I'm learning on Cessna 172R (2-9 Delta).
The actual flying part is relatively simple, but there's a tremendous amount of arcana surrounding it. You can tell a lot of what goes into flying dates back 100 years before GPS was invented since you have to call in and get weather reports each hour so you can dial in barometric pressure into the gauges (unnecessary if you used GPS-based instruments), and access arcane weather reports that have random digits dropped from various numbers (no doubt an artifact from the days when mainframe storage was expensive and fixed-column data was the standard). The obscure and arcane nature of much of this probably contributes to accidents and errors that could otherwise be avoided with modern technology.
My goal is to get my certificate and eventually a twin-engine rating. I hope to buy either a Ciruss SR22 or maybe go on up to a Beechcraft Baron 58 twin engine. The Baron 58 has a lot more capacity at take off so you can carry a realistic load of passengers plus enough gasoline to make it to the end of the runway.