Mindfulness is widely recognized as an effective technique for managing mental and physical health. However, a significant challenge remains when attempting to transform its practice into a habit. To understand the individual characteristics and contexts that correlate with habit formation experiences, we conducted a six-week observational study involving 62 participants who planned to adopt a new mindful breathing habit. Overall, 47.4% (N = 1,234) of daily surveys were completed and 41 participants completed the post-study survey. Using a growth curve modeling framework, we confirm the presence of significant overall change in habit automaticity across participants in the first 21 days of habit practice. Furthermore, we identify four factors that are significantly correlated with the gradient of participant habit formation trajectories: how committed a participant is to building the habit before starting the practice period, their prior mindfulness experience, and two dimensions of personality – agreeableness and emotional stability.