Hi,
I am new to electronics and I am finding it very hard to keep motivated when I am struggling to remember all the rules. I read and read, and I am finding that it is hard to remember what I have read ...
You need to figure out how you learn best. I think most technically oriented people (like most of us here) absorb things faster and more permanently working with their hands, rather than just reading. When you do this, there is a mystery, or problem to solve, which triggers the brain to take the issue seriously. Personally, I can read something and forget it within minutes, but I remember all the details of real problems I've worked on decades ago.
Definitely, it's good to do hands on work as others are suggesting. However, sometimes it is difficult to find the time to do enough projects to learn everything you want. So that's where working on exercises/homework helps. I find that solving problems on paper can trigger the same memory retention as hands on circuit building, because I'm writing equations and diagrams with my hands, and trying to figure out a solution. And, the combination of hands on work with theory verification is very effective. Using circuit simulators like SPICE also seems to have the same effect.
Another trick, when you do need to just read information, is to rewrite all if the important information and draw diagrams, almost as if you wanted to write a book for someone else to learn from. This is a little time consuming, but not too bad if you can type fast in a word processor. Not only will you absorb the information very well, but you then have a handy reference book that is better than any book you can buy, because you made it the way you want. This last trick I just figured out in the last couple of years working on very complex engineering problems outside my areas of expertise (I'm 45 years old now). I wish I figured this out back in college.
The above is not necessarily easy, but a little discipline and a little love of what you are doing goes a long way!