M.G.
I know how you feel. When we are chasing around a little ones all of the time AND trying to maintain a home, I think sometimes we forget to take care of ourselves. It is SO easy to not eat right and not exercise. And without that, are bodies try to save all of the fuel (food) for energy that we do take in as a "survival" mechanism.
Consider eating 4 to 5 small NUTRITIOUS meals a day. Also taking a B6 vitamin after breakfast and then again after lunch. B6 helps our bodies metabolize food for energy.
It isn't instant, but with consistency it will give you more energy and motivation. Who knows, you may even loose a couple of pounds while you are at it.
One more thing, if you get bad PMS, the B6 is great for easing that tension as well.
Good Luck and hang in there,
M. :-D