Habits are actions that seem insignificant in the moment, but whose effects compound so that the long-term effect is significant. If you become 1% better every day, you will be very good after a year. The habit loop is subconscious and consists of four steps: cue, craving, response, and reward, thus you should target one of these steps to create a habit on top of something you already do, and altering the environment so it’s easier for you to do it. This is better than forcing yourself to do things. Lastly, pick areas that you are naturally good at, and set the pace to be a balance between boredom and being overwhelmed.
Overall, mostly a set of sensible advice about forming habits and sticking with them. I didn’t get much out of this book though, because I already do pretty much everything that’s recommended in this book. Although I didn’t think of them in terms of cue / craving / etc, I found them by introspection of my own behavior over the years.