Active2Gether

INTERVENTION: A2G intervention will be delivered through an web‐based app, adjusted for the intervention condition. The A2G intervention – including tailoring based on the computational model – will be compared with: (a) the A2G intervention with random coaching messages, (b) the Fitbit condition, where participants will only receive a Fitbit device and access to the Fitbit website, (c) the control group, where the participants will solely receive general information about physical activity through the A2G app. CONDITION: Healthy volunteers, Cardiovascular prevention, Metabolic health ; ; PRIMARY OUTCOME: levels of physical activity (moderate, vigorous, moderate‐vigorous); minutes of moderate‐vigorous per week after 3 months SECONDARY OUTCOME: number of stairs taken per week, weekly minutes of sports participation, weekly minutes of active transport ; ; levels of self‐efficacy, outcome expectation, social norm, intention, self‐regulation after 3 months ; INCLUSION CRITERIA: Healthy young adults aged 18‐30 years living in the Netherlands and Dutch speaking