What's your cure for being exhausted and grumpy?

I find that working 9–5 leaves me grumpy and miserable and in such a yucky mood at the end of the day… I guess mostly just very tired (I’m not good at waking up at 6:15am).

Do you ever feel like this? What do you do?
Please don’t say go to the gym, because I can’t get myself to do that when I’m at my best.

Are there vitamins? Some sort of pick me up that isn’t detrimental to my health?