Despite the unequivocal benefits from regular physical activity many obese people continue to live sedentary lifestyles which may be attributed to negative perceptions about exercising. This study investigated the acute psychological response of obese individuals to a single self-selected paced aerobic exercise session using the Subjective Exercise Experience Scale (SEES) and the relationship with Body Mass Index (BMI). Six obese volunteers, mean age 43.8 (range 38-50) years and mean BMI of 38.5 (range 30-44) walked 2 km outdoors at a self-selected speed wearing a heart rate monitor. Immediately pre and post a bout of walking, participants completed the SEES, measuring Positive Well Being (PWB), Psychological Distress (PD) and Fatigue. The walking intensity (114.5 plus or minus 17.4bpm) corresponded to 65% of the participant's predicted maximal HR. Walking time was 26.5 plus or minus 3.4 minutes. Wilcoxon Signed-Rank Test showed no significant change post exercise in PWB (18.2 plus or minus 5.4 to 20.3 plus or minus 4.0, p=0.07), PD (5 plus or minus 1.7 to 4.2 plus or minus 0.4, p=0.29) and Fatigue (7.7 plus or minus 3.0 to 9.8 plus or minus 3.3, p=0.14). Spearmans Rho demonstrated significant correlations between BMI and HR (r=0.94, p=0.01), BMI and Walk Time (r=0.89, p=0.02), BMI and Fatigue Pre (r=0.93, p=0.01), BMI and Fatigue Post (r=0.88, p=0.02) and BMI and PD Pre (r=0.85, p=0.03). PD Pre was also significantly correlated with Fatigue Post (r=0.84, p=0.04). Physicians should be aware of greater apprehension and possible psychological stress leading to increased feelings of fatigue after exercise with increasing BMI when encouraging walking for exercise. The levels of PD and Fatigue however were not high suggesting obese individuals generally did not have negative feelings regarding a single exercise session.