Whereas exercise-induced mood enhancement has been well documented, the relationship between mood and exercise participation is less well understood. Mood states influence evaluative judgments that could plausibly influence a decision to exercise. Further, most exercise-mood research is limited to normal weight adults in response to a single exercise session. The current investigation examines the influence of (a) morning mood on exercise, (b) exercise intensity/duration on mood enhancement, and (c) daily change in mood on exercise days compared with nonexercise days in obese behavioral weight loss program (BWLP) participants. Participants (N = 36) recorded morning, evening, and pre- and postexercise mood, as well as the type, duration, and intensity of exercise. Within-person analyses indicated that (a) morning mood was associated with an increased likelihood of exercising, (b) mood ratings were higher following exercise of greater intensity and duration, and (c) daily mood enhancement was associated with greater exercise initiation and greater exercise intensity. Measuring mood before and after exercise may yield important clinical information that can be used to promote physical activity in obese adults.