In my case, I am currently working through SICP (mid Chapter 4) and I use a highlighter to mark the key concepts presented in the book. Once I'm done with a cha

In my case, I am currently working through SICP (mid Chapter 4) and I use a highlighter to mark the key concepts presented in the book. Once I'm done with a chapter, I have a Google spreadsheet where I maintain lists of the concepts explained in each chapter. Every now and then, I sift through those lists at a glance and see all the new knowledge that I have been exposed to. Also, I am doing all the exercises which are saved in my Dropbox folder. Again, once I am done with a chapter, I post them in my blog. That helps me a lot in keeping a feeling of progress and accomplishment.