yes! You should change that running goal asap!! I'm into being realistic, so changing a goal based on current realities...yes, please!
It certainly makes me feel good if I stick to a goal and achieve it - that feeling of satisfaction is perhaps why we set goals to begin with - to get that great feeling of accomplishment. But I don't think I've ever beat myself up too much for not attaining something (that's what rationalizations are for!)