Design is a learning process in which new knowledge is constructed and used to shape the environment in ways that did not previously exist. Because design is about creating that which does not yet exist, when individuals engage in the design process, they face uncertainty about final outcomes. Drawing on psychological research, this paper presents a grounded theory to explain how the practice of low-fidelity prototyping allows practitioners to remain committed to the design process despite uncertainty about final outcomes. When enacting the low-fidelity prototyping practice, practitioners break larger tasks into modest size tasks. Modest size tasks allow practitioners to take frequent action. By taking frequent action on manageable tasks, practitioners experience small wins by observing their impact and attributing success to their actions. Through a series of small wins, they attribute the positive effects to self-action and reduce anxiety of failure and increase a sense of perceived control. This sense of perceived control allows them to remain committed to the design process despite the uncertainty of the outcomes.