A large part of the joy of programming comes from creating solutions to problems. So just look around and look at things you find annoying and think about how automating it might make your life easier.
Even if it looks like it might be too difficult to program a solution right now, there's nothing more motivating to learn more about programming when you're trying to solve a problem that will benefit you personally. And the feeling of pride and accomplishment will be that much greater too.
Just in the context of MangaDex, I found it annoying that there's no way to check the
feed filtered by translated language (chapters translated in languages I'm not interested it will also push a title up in the feed). Fortunately MangaDex has an API, so I built a way to easily access a filtered feed complete with a marker to show what the last chapter I read in the feed is. It's simple and makes my life just a little bit more convenient.