A Mobile App to Improve 24-Hour Movement Guideline Adherence in Preschoolers

The goal of this clinical trial is to evaluate whether a home-based mHealth intervention can improve adherence to the 24-Hour Movement Guidelines in preschool-aged children (3-4 years old) who currently meet 0 or 1 of the guidelines for physical activity, sedentary behavior, and sleep. The main questions it aims to answer are: * Can the intervention increase the proportion of children meeting all three 24-Hour Movement Guidelines (physical activity, screen-time, and sleep)? * Is the intervention feasible for parents to implement, as measured by a parent feedback survey? Researchers will compare an intervention group to a waitlist control group to assess whether the intervention leads to increased guideline adherence. Parents and Participants: * Children will wear an accelerometer to track physical activity and sleep patterns. * Parents will use a mobile app that delivers weekly lessons and behavior-related goals to encourage healthy movement behaviors in their children. * Parents will complete questionnaires on their child's movement behaviors and development at baseline, 6 weeks, and 12 weeks. * Additionally, children will undergo motor skills assessments, and parents will provide feedback on cognitive development and behavioral changes.