Welcome GA Novice,
The best way to learn the theory is to "want to know". It's easier to learn the theory if doing so is answering questions that your mind already has, rather than trying to force information into a file cabinet which will not open. Prime your natural inquiry enough that you have questions you really need the answers for, and then read the books for the answers, and you'll recognize and remember the answers, and thus the information much better. There's no point in memorizing a whole bunch of information, without really understanding why, nor how to apply it. Have the reading you do answer your questions.
You can find questions by reading accident reports. Why did the accident occur? What were causes and factors of the accident? (reports are pretty clear to identify them). Ask yourself how that won't happen when you're flying - what will you do to prevent all of those factors? When you have considered factors of meteorology, performance, systems, weight and balance, and handling in adverse surface winds, you'll be well under way! These will show up as factors in accident reports over an over (we pilots don't always learn the first time around!). That should perk your "why?" interest, and make studying more valuable...
I've been flying GA airplanes since 1974, and I can still find something to learn by reading about them!