1) The book discusses how to build good habits and break bad ones using a four-step model of cues, craving, response, and reward. It explains how to design each step to either strengthen or weaken a habit.
2) Specific techniques include habit stacking, temptation bundling, designing your environment for success, using commitment devices, finding an accountability partner, and tracking habits with a simple checklist.
3) The book argues that habits are largely context-dependent and influenced by their surrounding environment. It's easier to avoid temptation than resist it, so reducing exposure to cues for bad habits makes them easier to change.