Young inactive healthy-weight females (n = 42) were randomly assigned to exercise at a self-selected pace on a treadmill beside a confederate who was providing either intrinsic or externally regulated verbal primes. Heart rate (HR), rating of perceived exertion (RPE), percentage of time spent in moderate-to-vigorous physical activity (MVPA), and exercise continuance were recorded. Participants completed a self-report questionnaire assessing mood pre- and postexercise session and postexercise motivational outcomes. The intrinsic motivation group reported higher RPE values after 8 min of exercise, had higher recorded HR measures at all 5 recorded time points, exercised at a higher %HR max, spent more time in MVPA, and were more likely to continue to exercise than participants in the externally regulated motivation group. A time effect was noted for vigor. Based on these findings, exercise motivation can be "contagious" through verbal primes, suggesting that exercising with or around intrinsically motivated individuals may have beneficial outcomes.