* While reading, tag you book in interesting parts, but don't break you flow. Have the tags at hand.
* Use something like anki or mnemosyne to dump all your tags.
* Enjoy what you are doing. This is connected to the first suggestion.
* Sleep well, exercise at least 5 times at week, eat healthy, and socialize.
"Study what you feel like in this list."
That's part of the problem. Some items crowd out others. And there are a lot of items. :)
Since I often don't follow up on setting aside explicit time to focus and study and practice, I end up focusing on some things to the exclusion of others.
That may be a way of telling myself the effort isn't worth it. But I think it's really me just doing what seems easiest. While it helps to enjoy what you're trying to learn, there are future benefits to things that may not be that enjoyable now (like practicing the violin).
That's why I'm trying out assorted "learn in the background" sorts of things. Like running a flash-card app or playing German language videos while coding; it's sort of on the peripheral, but I still pick up some things.