The starting point for the project One, Two, Three, Social Game! is what we observe in everyday youth work practice: weaker peer bonds, increasing loneliness, and declining movement habits, which affect mental wellbeing and young people’s readiness to engage in social life. European data confirms these observations: in the EU, around 45% of people declare that they never exercise or play sport, while in Poland this indicator reaches approx. 65%, and in Greece approx. 68%. At the same time, studies on young adults in Europe show that loneliness in this group is widespread (more than half of young people report loneliness at a moderate or high level). During the European Year of Youth, young people identified as key needs, among others, improving health and wellbeing, strengthening education/skills, and responding to socio-economic and environmental challenges. Our project responds to these needs by combining physical activity with community-building and empowerment. We implement the project as an intervention based on non-formal learning: regular movement, team games, integration activities and social games are tools to strengthen social, civic and intercultural competences—rather than goals in themselves. This approach is consistent with the Erasmus+ logic in the youth field, where mobility activities are meant to equip young people with competences and strengthen their active participation in society through non-formal and informal learning. In addition, the project promotes safe, daily health micro-habits at least 30 minutes of movement per day as a realistic starting point—aligned with global recommendations on youth physical activity. Project objectives: 1. Strengthening wellbeing and peer relationships through team-based activities, daily reflection groups and safe, inclusive work in international groups. 2. Increasing physical activity and health agency: participants will develop their own micro-habits plan movement + recovery and test a set of activities that can be replicated locally. 3. Increasing social participation: each national team will prepare and implement a standard follow-up action (a local sport-and-social initiative), transferring the mobility experience into their communities. 4. Inclusion and equal opportunities: the project is designed not to create barriers (organisational, economic or competence-related) and to genuinely include young people with fewer opportunities, also in the role of co-creators of activities. We base recruitment on real, existing youth environments of the partners and conduct it in a way that ensures group cohesion. Before the mobility, we carried out a short local needs assessment, which set our baseline for the objectives and helped us tailor support, including for young people with fewer opportunities. We will measure outcomes using a set of simple KPIs, and we will strengthen sustainability through a shared follow-up standard and results reporting, so that the project is replicable and scalable also beyond the participant group. As a result, One, Two, Three, Social Game! is a practical project because it connects movement, relationships and empowerment building a bridge between Erasmus+ mobility and real change in local communities in the areas of health, wellbeing and youth participation.