A key mandate of environment education (EE) is to motivate people to engage in environmentally responsible actions. However, school-based EE has not been successful in nurturing environmentally responsible actions in students. This is partly because of the information-oriented structure of current EE, which assumes that symbol-based knowledge directly leads to motivation and action. In contrast, educational initiatives based on practices and actions in the world, with farming as an important component, have been successful in creating transformative changes in behavior. To develop similar transformative interventions that motivate school students, it is necessary to understand the general psychological principles that make such participatory designs successful. Here we report a year-long observation study that seeks to contribute to such a general model, analyzing how farming actions changed the motivation of volunteers working in an urban community farm. We take an analysis approach inspired by recent embodied cognition models, where volunteers' lived experiences and interactions with material entities are analyzed, to understand how motivation and values develop through such interactions. Based on this data, we propose a spiral model of motivation and action, where specific farming actions coalesce together to form motivation and values, which then seed wider environment-oriented actions in the world.