One of the best parts of LLwN as a way to study is the passive encouragement: you can click on a word to mark it as "known", and then it always shows up green in future subtitles.
Pretty soon, entire multi-line subtitles start showing up all green. And for me at least, that provides a huge confidence boost that helps me keep going.
Instead of seeing each new subtitle as a challenge ("<Deep breath> here we go..."), you think, "It's all green! I already know everything here! I just have to read it!" And that's made a huge difference in how it feels to study.
I wish Kindle had a similar feature for books.