Preservice students do not always see the relationship between the theories they learn in motor development class and the practical applications of those theories in the gymnasium. This article begins to bridge the gap between theory and practice. Within the theoretical viewpoint known as the ecological perspective, the authors identify the practical, user-friendly notion of "constraints," which are not considered good or bad. In practical terms, physical educators must consider many constraints and their changing influences to determine the best way to promote the development of motor skills; in other words, everything matters and everything changes. Because characteristics (constraints) of the individual change far more slowly within the context of a day-to-day physical education setting and are difficult to control, physical educators must focus on making modifications in environmental and task constraints as a way of promoting interactions that will allow the developmental progression of motor skills. Several different examples of manipulating these constraints are provided.