I echo what everyone else has said, and I'll just add that I've been in mourning since my last big, euphoric hypomania about 3 years ago. I miss my manic-self. In some ways, it is the best of myself, in some ways not so much, in some ways the worst (depending on the episode), but when I'm high, as someone else said, there can't possibly be any drug that can compare to that tremendous feeling.

I also feel flat. And I wonder if I really am flat, mood-wise, or it's just what I feel in comparison to hypo/mania and that's what it's about. Maybe if you think of it like that, it might help: that you're not actually flat, but it's just that you've come down from the mania and in comparison, that's how you feel. Maybe once you're further and further away from the mania, you won't feel so flat any more. I hope that for you.