Pediluma is a shoe accessory designed to encourage opportunistic physical activity. It features a light that brightens the more the wearer walks and slowly dims when the wearer remains stationary. This interaction was purposely simple so as to remain lightweight, both visually and cognitively. Even simple, personal pedometers have been shown to promote walking. Pediluma takes this a step further, attempting to engage people around the wearer to elicit social effects. Although lights have been previously incorporated into shoes, this is the first time they have been used to display motivational information. Published at TEI 2011.