Despite billions invested in community-based obesity prevention, most programs are not delivered long enough to improve population health. Modelling shows interventions must run for at least a decade to impact childhood obesity, yet fewer than 20% of public health programs continue beyond two years. This cycle of promising starts and premature endings is now routine. While implementation science has strengthened program delivery, the field has largely overlooked what happens after programs begin. Sustainment i.e. the continued delivery of effective programs after initial support ends is rarely studied, with less than 1% of public health research addressing it. Guidance on how to plan for and support sustained delivery remains limited. This presentation will identify common system-level threats to program sustainment, synthesise what is known about strategies that support program longevity, and introduce practical tools to help policymakers and practitioners embed sustainment into program design from the outset. By shifting focus from ‘getting programs in’ to ‘keeping programs going’, we can help ensure that public health investments deliver on their long-term promise.