Looking to try and learn something new.
Taking small gadgets apart for cleaning and fixing. It may sound like it's complex and a lot of work but in reality only needs a small investment of tools and patience. Pretty much every item that can break has a playable step by step youtube guide on how to fix it, clean it and even DIY modify it. Youtube is a powerful thing, and doing just a few small diy projects can tremendously increase your skill level. A long time ago people used to repair things, now we live in a world of disposable items. It's amazing how many can actually be quickly and easily fixed.
Getting into a proper fitness routine.
Using a pressure cooker to make moonshine. Okay, more seriously. I taught myself how to write apps. Took about a month to get a decent basic one that I wanted and then I was able to tweak it and learn more. There's free app developer software from MIT to use MIT App Inventor and I reckon there is something similar for iPhone apps.
Riding a bike.
Driving a car.
knot tying a few basic and super handy knots.
also how to make insanely strong rope from wild grasses. https://youtu.be/DljWyRQFrNc