As I have told my kids many times, nothing is hard if you work at it. (Of course you have to dothe hard work in order for it to finally become easy.)
It's all a matter of priorities. In a typical day, I make it through less than 10% of the things I want to do. Many of the things that don't make the cut are important and I would dearly love to do them but there just isn't enough time.
Studying and understanding your ideas, and learning more mathematics and physics, are all on my list, but there are more important things I want to do with my time. The important thing to me in this subject area has been to understand the universe at a sufficient level to relieve me of the anguish planted in my mind by my early religious teachings. I don't like the idea of a single animal suffering, but the prospect of billions of people, including most of my friends and relatives, suffering endlessly was just too awful for me to be comfortable with. I don't claim to know or understand anything now, but at least I have enough of a vague glimmer so that I no longer believe in that gruesome prospect. I am no longer compelled to try very hard to understand things much more. I am casually interested, though. It's still fun to think about, but I am not going to work very hard at it.
I am sure I would enjoy re-reading "QED", but you should see the stack of books I have that are waiting in line ahead of it. Don't hold your breath.
Make sure you don't miss Langan's essay called "Intruduction to CTMU" at