I go through Meditations on a regular basis. I have found it to be singularly uplifting. It has never "flattened" my emotional state at all, but I'm not surprised that flattening is an outcome for some readers.

It's possible that the translation you're using gives the text a morose tone. On the other hand, I've enjoyed both of the translations I've read (My current one is Maxwell Staniforth's and George Long's.)