Automate something (my favorite advice), or analyze something. Find a task that has a lot of manual steps (copy a file here, copy a string from there, etc) and automate whatever you can.

Pick something apart and analyze it programatically. Email is great as there are protocols and libraries to do this with. Find a/the IMAP library for your language of choice, copy a bunch of messages to some place where you won't harm the originals, and start picking apart the folders and messages. See what you can know about what's in a folder and list it. See what you can know about a message, and list that all out.

You could do the same with a bare html document, there are really good libraries to pick apart an html doc. Beyond that, learn the DOM and pick it apart from that angle.

I started with a command line calculator when I was 17(Internet was a luxury for me back then.)

You can try your hand at algorithms. You can implement them in a language of your choice, try different methods, try to speed things up etc.

If you are in to math, you can try projecteuler.com, it is a good learning source, provides lots of interesting problems to solve.

You can check code katas. https://en.wikipedia.org/wiki/Kata_(programming)

The idea is not that important at first. By doing even simpliest things, you will expand your knowledge on programming, which in turn will guide you about what you can do with it.