This chapter synthesizes prominent motivational frameworks to explain how CLIL influences engagement in PE. Self-Determination Theory (SDT) posits that learners are intrinsically motivated when autonomy, competence and relatedness needs are met. Achievement Goal Theory differentiates between task-oriented goals (focused on mastery) and performance-oriented goals (focused on outperforming others), while Attribution Theory examines how interpretations of success or failure shape persistence. The chapter discusses how CLIL can foster intrinsic motivation by embedding language tasks within meaningful physical activities and by offering opportunities for autonomy and cooperation. It also addresses gender differences and suggests strategies—such as cooperative competitions and scaffolding—that can enhance participation among girls. Finally, the chapter offers practical guidelines for tracking and sustaining motivation through self-assessment tools, observational protocols and tailored feedback.