I agree with this completely. There is no reason to let the riff-raff bring you down. Maintaining your cheerfulness in the face of all the stupidity, fecklessness and greater idocy around you isn't easy - but it will strengthen you if you learn to see beyond it. We here wish to be conquerors not be brought low by the herd. Read - truly read your Nietzsche...it will bring you wisdom in this regard.
Was Nietzsche ever cheerful? He rambles on about the importance of being joyful all the time, yet it's all a bit hard to swallow when his life was in near-ruins and he doesn't have more than emotional arguments for it. It's not too far of a stretch to say that the original post in this thread could have been written by Nietzsche himself. It's strange - whenever I am truly cheerful I can't stomach Nietzsche. It's only when I let the riff-raff bring me down that I can see eye-to-eye with him.
ASBO already put some perspective on this. But I would also add, that I recommended a good reading of Nietzsche - not to emulate him or his life. Many a good thinker cannot live up to his own ideals, or may not even try to. Nevertheless, It is Nietzsche's lofty ideas that I find inspiring - in cheerful times and darker stretches alike - though perhaps for different reasons.