--- - |2 Abstract Across three experiments, we show that a change in the levels of physical activity increases creative thinking, whereas inactivity or repetitive activity lowers it. Participants walking forward were more creative the first few minutes of initiating physical activity than those sitting, or those merely watching changing scenery, and these effects dissipated when they continued the forward movement over time (within 8 minutes). Furthermore, merely anticipating a change in physical activity, for example, when participants were aware a task is coming to its conclusion, also increased creative thinking. We hypothesize that a change in physical activity cues the need to navigate new situations, and thus, can increase mental flexibility and creative thinking to deal with new circumstances. But once people habituate to their physical state, either of being at rest or being in motion, their level of creative thinking also returns to baseline levels. We confirm that mood, feelings of achievement, and energy are not responsible for the observed effects. - The Journal of Creative Behavior, EarlyView.