Given its origins in high-income countries, the field of physical activity and public health research and promotion has broadly followed a choice-based model. However, a substantial amount of the physical activity occurring routinely in many settings, particularly in low- and middle-income countries (LMICs), is the result of economic necessity and is not due to true, free choices. We propose the necessity- versus choice-based physical activity models framework as a conceptual tool to ground physical activity and public health research and promotion efforts in LMICs, helping ensurethat these efforts are relevant, ethical, responsive, and respectful to local contexts. Identifying ways to ensure that LMIC populations can maintain high levels of active transport while increasing opportunities for active leisure must be prioritized. To promote equity, physical activity research, programs, and policies in LMICs must focus on improving the conditions under which necessity-driven physical activity occurs for a vast majority of the population.