In response to the challenges faced by China’s aging population, including mobility restrictions, health concerns, and social isolation, calls for innovative approaches to enhance their physical and mental well-being. Square dancing, or ’Guangchang Wu’, is a communal activity where Chinese elderly gather in public spaces to dance together, combining exercise with social engagement. We developed VitalStep, an online co-dancing app tailored for people aged 45-70 to participate in square dancing virtually. Through collaboration with square dance communities, we ensured our app met the needs and preferences of its target users. Early findings suggest that the app successfully motivates seniors to be more physically active and socially engaged.