This document describes a study that examined the importance of emotion tracking for behavior change. The researchers conducted interviews to explore how emotions influence unwanted behaviors. They then deployed a system where 35 participants logged information for an unwanted behavior over 21 days. Participants using an Emotion-Focused system to record emotional consequences of behaviors showed more successful behavior change. Analysis showed greater engagement of negative affect for unsuccessful days and increased insight were key to motivating change. The study provides implications for improving behavior change technologies with emotion tracking.