In the Netherlands, only 55% of the Dutch population meets the norm of 150 minutes of moderate physical activity per week. To increase overall physical activity, the Dutch government wants to stimulate active travel. Active travel has two important benefits: the accessibility effect and the health effect. Yet, the effect of active travel on the total net health benefits is not completely understood and “wrong” conclusions can be made if the complex causal relationships between active travel and health are overlooked. In this research, two hypotheses are tested that are a possible explanation for active travel to not have the same health benefits as physical activity: 1) active travel substitutes for other forms of physical activity, 2). there exists a causal bi-directional relationship between active travel and health. Leisure physical activity is used to examine other forms of physical activity. BMI and general mental health are used to examine health. To test the hypotheses, the Cross-Lagged Panel model is used and is estimated on the LISS Panel data. The findings indicate that there exists a positive effect between active travel and other forms of physical activity. Furthermore, this research indicates no relationship between active travel, BMI and mental health. Especially, the findings of the positive effect of active travel on other forms of physical activity are uplifting. This means that the current health benefits are underestimated. We recommend that these values will be changed in future reports regarding the health benefits of active travel.