I sometimes feel the same. I find that I have to break the cycle by forcing myself to get exercise (usually a brisk walk for 30 to 45 minutes). When I exercise I have better energy overall, and my mood is definitely better. Of course, "forcing myself" is the key; some days every fiber of my body and every thought argues against getting my butt up off of the chair.
I suggest committing to some daily exercise for a few days in a row, and no matter what get yourself out and moving. Don't accept any excuses. You should eventually feel at least a little better.