I certainly hope not because if a recent study holds true, if thinking about exercise causes your heart to race you're twice as likely to die of a sudden heart attack.
Of course it occurs to me that the folks whose hearts are likeliest to race at the thought of exercise would be those who are the least fit as they'll be worried about the prospect of exercising which in turn might cause their adrenaline to flow and their hearts to race.
So perhaps the results aren't so surprising - those who are the least fit are the most likely to suffer sudden heart attacks.
Bottom line? We should all do more exercise.
Jouven, X., Schwartz, P., Escolano, S., Straczek, C., Tafflet, M., Desnos, M., Empana, J., & Ducimetiere, P. (2009). Excessive heart rate increase during mild mental stress in preparation for exercise predicts sudden death in the general population European Heart Journal DOI: 10.1093/eurheartj/ehp160