Today, society exults those who "work on themselves" and commit to self-improvement through changing habits, either by breaking bad ones or making good ones. New Year's resolutions are a major tradition in American culture, and everywhere you look there are articles and social media influencers promising ways to help create healthy habits in diet and exercise, improve concentration, fix relationships, and boost mental health. The articles in this volume consider how habits are created or broken from a scientific perspective, offering psychological insight into the processes involved in self-improvement and why it can be so challenging to change habits.