When I was in college my professor tried teaching us regular expressions: the theory, the algebra, all that. I left dumbfounded. When I hit the Real World I quickly ran into many practical use cases where a regular expression helped me solve a problem. That’s when I finally grokked them.
If you want to improve your understanding (and deployment of) regular expressions to solve problems, but don’t have a use case at the moment… here’s a whole bunch of them for you to practice on in the meantime.