Really neat. This kind of simple approach to behavior improvement really resonates with me.

I'm working on a (web) app that takes a similar approach to improving spending habits. It's the same idea that you track progress not merely in terms of bare numbers, but that you can also record some context and notes about improvement.

Have you thought about adding support for sharing progress with other users? For example, I could think of a friendly reading competition with a friend where we try to build the longest streak and daily note what we've been reading.