Previous research suggests that a range of factors influence an individual’s physical activity (PA) participation, but studies among Nepalese adults are limited. In this qualitative study, we aimed to explore the multilevel influences upon PA participation among community-dwelling adults aged 40 years and above living in an urban setting in Kathmandu, Nepal. Men ( n = 21) and women ( n = 30) were purposively sampled to participate in one of nine focus group discussions. Types of PA undertaken constituted activities related to housework, farm work, and active travel. Individual-level barriers included lack of knowledge, lack of motivation, perceptions of already being active, personal limitations, and lack of time. Interpersonal barriers included household responsibilities and lack of support. Broader environmental barriers included lack of infrastructure for active commuting, poor safety, rising use of motorized transport, lack of resting areas, weak social norms about PA, declining agricultural engagement, mechanization, and improved access to technology and facilities. Some differences were observed between the gender and disease groups. Health benefits, integration into domestic work, opportunities for social interaction, and social support were the facilitators. Interventions focusing on families, highlighting the short- and long-term benefits of PA, addressing gender roles, and ensuring women are better supported represent opportunities to promote PA. Community-based interventions will be essential to establish social norms around PA and improve social support.