Many programs to increase physical activity have been evaluated in developed countries, where 'leisure time physical activity' is the most frequent domain for interventions. In developing countries, and also with reference to global obesity prevention, different kinds of interventions targeting 'total physical activity' are needed. This requires efforts across agencies and sectors, and in the domains of work, active transport, reduced sitting time, as well as leisure time physical activity promotion. In considering possible solutions, this commentary examined the use of complex systems, where integrated efforts across sectors and agencies might, in combination, contribute to increasing total physical activity. The key sets of actions required globally to increase physical activity were, in our opinion, [i] efforts to disseminate individual-level behavior change programs to reach much larger populations rather than volunteers, [ii] social marketing and mass communication campaigns to change social norms in the community and among professionals and policymakers, [iii] efforts to influence the social and physical environment to make them more conducive to physical activity, and [iv] the development and implementation of national physical activity plans and strategies, with sufficient timelines and resources to achieve measurable change.