Physical activity (PA) is a key determinant of physical and mental health, yet inactivity remains prevalent globally. Digital fitness (DF) technologies, including mobile apps, wearables, and virtual coaching, have emerged as tools to promote home-based PA. However, prior research has not comprehensively examined how multiple DF technologies influence PA adoption and habit formation. This study investigates the relationship between DF adoption, DF use habits, and PA behavior at home, focusing on preparatory PA habits. Using a cross-sectional survey of 486 Spanish healthy adults, we assess DF adoption across eight DF types and examine its association with PA stages of change (SoC) and preparatory PA habits. Results indicate that DF adoption, measured as the total number of DF used per individual, correlates with higher PA SoC at home, with DF use peaking in early behavior change stages. While DF adoption does not directly predict DF use habits, habitual DF use is significantly associated with preparatory PA habits, which are strong predictors of PA engagement. These findings highlight the role of DF in fostering PA behavior and suggest that developers should tailor features to support users in different PA SoC stages. The study contributes to IS and PA research by integrating habit formation theories and emphasizing the need for DF technologies that facilitate PA initiation and maintenance.